# Hot Math Posts

### How To: Evaluate square roots

This is the video about how to evaluate square roots. The square root of a number is a number that you can square to get it, that is, a number that you can multiply by itself to get the number. So, 2 is a square root of 4, because 2 x 2 = 4, and 3 is a square root of 9, because 3 x 2 = 9. (-2) x 2 is also 4 and (-3) x 2 is also 9. Numbers that have square roots always have two, a positive one and a negative one, but the square root symbol means only the positive one, so we can have one answer...

### How To: Derive the area of a circle

This video is about deriving the area of a circle of radius 'r' using polar co-ordinate. First, we draw a circle and its radius 'r'. Then draw another radius close to it, so that it forms a small triangle-like figure. To find the area of the complete circle, divide the circle into similar small triangles. The area of each triangle is given by half the product of its perpendicular and the base. We give the angle between the two radii as d?. We get the area of the small triangle by substituting...

### How To: Rationalize a denominator that contains a surd

In this video, we learn how to rationalize a denominator that contains a surd. First, you need to rationalize the denominator by removing any square root sign. To do this, you will multiply the fraction but the flip of the denominator over itself, with the square root. Then, you will multiply the top by the bottom with the square root and this will remove it from the equation once you do the math to multiply it out. Once you're done, the number will be rationalized and you will have the answe...

### How To: Find measure of an exterior angle of a regular polygon

This tutorial the shows how to find out the measure of an exterior angle of a regular polygon. He shows the formula to find it which is 360/n, where n is the number of sides of the regular polygon. He goes on further to explain the formula by taking an 18-sided regular polygon as example and computes its exterior angle as 360/18, which is 20 degrees. If you are looking to compute the exterior angel of a regular polygon, follow the procedure given in this tutorial.

### How To: Deal with brackets in polynomials

This how-to video shows viewers how to solve math problems with brackets in polynomials. The person in the video teaches people how to solve the problem with a positive sign before the brackets. This segment does not show how to solve the trickier problem where there is a negative sign in front of the brackets. The tutor shows everything from removing the bracket due to the positive sign, to combining the similar terms for the result of the problem. This video can help anybody deal with brack...

### How To: Find the volume of a swimming pool

In this video, we learn how to find the volume of a swimming pool. To do this, you will first need to find the measurements of all the sides that are on the pool. After this, you will plug in the measurements that you found into the equation to find the volume. This equation is: V=AH, volume= area(height). So, plug in the area and the height to the equation for A and H and then multiply these two together. Once you do this, you will find the answer! Don't forget to label the units on the fina...

### How To: Measure angles with a protractor in Geometry

Confused with how to use your protractor for Geometry homework? In this helpful video, Doug Simmons from free math tutoring provides easy to understand classroom examples explaining how to use both sets of numbers on your protractor. Provides easy to remember rules that will keep you from fumbling with the common confusions of protractor use. Doug also explains common mistakes that you should avoid in order to start getting the right answers in your math problems. Finally, math tutorials at y...

### How To: Find the area of an oblique triangle using formulas

In this tutorial the instructor shows how to find the area of an oblique triangle using different formulas. To find the area of an oblique triangle there are different formulae. The first formula to calculate the area of a triangle is area A = (1/2) * a * b * Sin(C), where a and b are the lengths of the two sides of the triangle and C is the value of the angle of the triangle that lies in between the two sides a, b. Now substitute these values in the given formula to find the area if you have...

### How To: Solve for the missing ratios or proportions

In this video the tutor shows how to solve the missing ratios or proportions. He explains it with an example, where a number in one of the ratios is missing and he intends to find this value. He shows the example of cross multiplication, where you multiply the values on the either side of the equation diagonally and finally solves the equation which results in the value of the unknown value. This is an introductory video explaining how to use rations and proportions to find missing values.

### How To: Determine the age of a fossil using carbon-14

If you have a fossil, you can tell how old it is by the carbon 14 dating method. This is a formula which helps you to date a fossil by its carbon. If a fossil contains 60% of its original carbon, how old is the fossil? The half life of carbon 14 is 5600 years. That means this is how long it takes for half the nuclei to decay. After 5600 years, if we start with a gram, we end up with half a gram. This rather complex formula shows you how to solve this puzzle using accepted scientific methods.

### How To: Use a TI-89 to calculate nCr

This video shows you how to do a mathematical representation on computing the nCr function using a TI-89 calculator. You can write the nCr notation in different forms. It can be simplified from nCr to C(n,r). The symbol can either be read "n choose r" or "n taken r at a time" which are from it's probability applications. On the example to find "26 choose 17", go to the Home screen of the TI-89 calculator and then go 2nd 5 which is Math. Go choose probability and then to nCr to type in (26,17)...

### How To: Simplify cube roots

In this video, the narrator presents the viewer with a quick, painless way of simplifying cube roots. The narrator presents many methods to simplify square roots to appeal to different learning styles. By doing things like dividing the power by the root to figure out the power of a number x, the viewer is better able to tackle square-rooting numbers that may not have friendly roots. The video gets more complex as it goes on, eventually teaching the viewer to split the inside of a root up if t...

### How To: Use derivatives to find slope in calculus

Need help figuring out how to work with derivatives in calculus? From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to use derivatives to f...

### How To: Solve a line integral over a closed path

Line integrals will no longer be the feared terrorist of the math world thanks to this helpful guide from the Khan Academy. Marvel at the ease in which the integral is taken over a closed path and solved definitively. Then take out a sheet of paper and see if you can do the same.

### How To: Simplify surds (improper square roots)

Could you use a little help figuring out how to simplify numbers left in square root form? Watch this free video lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this free math tutorial, you'll learn how to simplify surds.

### How To: Geometrically prove the Pythagorean theorem

From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps. With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to perform a geometric proof of the Pythagorean theorem.

### How To: Subtract fractions with borrowing

This how-to video describes how to subtract fractions using the borrowing method. The video shows viewers everything they need to know including basic subtraction of fractions, how to find common denominators, to the more difficult borrowing techniques. The narrator in this video does a great job of keeping things simple enough for anybody to understand. At the same time, he goes in depth enough that you really get how to use this technique. The voice in this video is very calm and clear. Thi...

### How To: Find the equation of the axis of symmetry

This video is about the Equation of Axis of Symmetry, The video is about the equation which is x = 3/4. In order to score correct marks for this equation, the gentleman in the video describes how and where to write x = 3/4, he says it has to be written on the graph, and the video contains the example graph. It is quite an interesting educational video, especially for those doing mathematics and want to learn more online, this video is very useful for students. There is more about the equation...

### How To: Reduce fractions to their simplest form in basic math

This video teaches us the method to simplify the fractions. Let us take an example of 18/24. Find a number that goes into both 18 and 24. Divide the top and bottom by the same number. Here, 2 will go into both numbers. So, the number now becomes (18/2)/(24/2) which gives 9/12. This fraction can be further simplified by dividing the top and bottom by 3. We get 3/4 which is our final answer. The fractions 18/24, 9/12 and 3/4 are called equivalent fractions since they are of the same size. Simil...

### How To: Find the area of a circle when you know the diameter

In this video, it is shown how to calculate the area of a circle where the diameter is given. The formula for calculating the area of a circle is pi multiplied by square of radius. Radius is actually half of the diameter. In this video, the diameter is given as 10.6 meters. Hence, the radius will be half of 10.6 which is equal to 5.3 meters. Now, to find the area we shall multiply pi with the square of 5.3. Square of 5.3 is 28.09. If we multiply 28.09 with pi we shall get the area of the circ...

### How To: Convert numbers in and out of standard form

In this video, we learn how to convert numbers in and out of standard form. Standard form is a useful way of writing down very large numbers and very small numbers. To do this, you will look at the number you have and ignore the zeros that are just at the end. Then, write down the basic numbers. Put a decimal point in this number to make it between one and ten. Now, write down x 10 and put the power for how many places the decimal point moved to get to the new number. This will help you write...

### How To: Calculate Type I (Type 1) errors in statistics

Need a quick primer on how to solve type-1 error problem in stats? Let this video be your guide. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps. For all of the details, watch this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials.

### How To: Find the equation of a tangent line

This is the video about how to find the equation of a tangent line. As you may recall, a line which is tangent to a curve at a point a, must have the same slope as the curve. Therefore, the slope of the tangent is m = lim f(a + h) - f(a) h-->0 h Since the slope equation of the tangent line is exactly the same as the derivative definition, an easier way to find the tangent line is to differentiate using the rules on the function f. For example, Find the slope of a line tangent to the function ...

### How To: Calculate percent error in chemistry lab activities

If you want to know how to calculate percent error easily, you should watch this video. Error is the amount of deviation from accurate values. Error calculation is not possible, unless you make a quantitative measurement of the various quantities involved in your experiment. Measurement can help us in calculating errors and knowing how right we are in our theoretical models. In calculating percent error, We need to get the experimental value and the value which you are aiming at, which is the...

### How To: Describe a linear system without graphing

This tutorial looks at how to describe a linear system without actually graphing it. In order to do that, you will need to convert both equations of a problem into the Y=mx+b format. Once you have done this, you will be analyzing the m and b values. There are a few rules to follow. If the slopes (or m) and the Y intercepts (or b) are equal, there are an infinite number of solutions (or dependent equations). A second rule is if the slopes are equal and the Y intercepts are different, then the ...

### How To: Find the square root of a number in basic arithmetic

From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps. With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to answer problems that require you to find the square root of a number.

### How To: Find X-bar with the Z-score formula

In this video tutorial it shows you how to find the x-bar by using the Z-score formula. In the beginning of this video the formula is displayed on the right, while the values that you need to plug in are on the left. Once you plug in the values and do the cross multiplying, all you have to do is get x-bar by itself on one side of the equation. This is a simple problem on using the z-score formula to find x-bar, it can help you solve more complex problems in the future.

### How To: Find the area of a rectangle

The area of a rectangle is the basis for all geometry. You will need to know how to do this in order to better understand other objects. This video tutorial will show you the formula for area of a rectangle and how to use it. Don't be confused in math class anymore.

### How To: Subtract mixed numbers with renaming with Mr Binkley

This video is about subtracting mixed numbers and renaming. 1. Start on the right side of the problem.

### How To: Understand the differences / similarities between squares, rectangles & rhombi

This math lesson from Yay Math covers four-sided shapes in geometry. Learn about the differences and similarities between rectangles, squares and rhombi (the plural of rhombus). The properties of rhombi and squares are covered, so sit back and enjoy this educational (and FUN) math lesson.

### How To: Find r-value & equation of regression line w/ EL531W

Need a little help in your Statistics class? In this statistics tutorial hosted by The Free Math Tutor, a demonstration of how to use the Sharp EL531W calculator to find the correlation coefficient (r-value) and the equation of a regression line is given. Want some more practice? For exercises and answer sheets, go here.

### How To: Calculate weight if given the mass

The video shows how to calculate weight if the mass is given and vice versa.Later on in this unit you will learn about Newton's laws of motion and Newton's second law of motion gives us a way to change mass into weight and vice versa.This law will tell you what is happening to objects when the net force on the object is not equal to zero and the easy way to say what will happen is that the object will accelerate.But how much the object accelerates depends on two things,firstly the mass of the...

### How To: Find extra points for a parabola (quadractic equation)

This is a mathematical educational video on how to find extra points for a parabola. In the first two examples there is no need for finding extra points as they have five points and have zeros of the parabola. In example 3 we need to find extra points. The equation is y=4xsquare-4x+4. You can take x= -1 and get the value for y. You will get a point now. Similarly you can substitute -2 for x in the same equation and get the value for y. Now you get another point. Now you can draw the parabola.

### How To: Simplify fourth roots

In this video the instructor shows how to find out the fourth roots of a number. The properties of fourth root says that for any positive number of a, its fourth roots are real. And for any negative value a, its fourth roots are not real. So split the number inside the fourth root as the product of two perfect squares and then cancel out the power with the fourth root giving its roots. As the fourth roots of a positive number are real, the answer you get is correct. But you cannot find out th...

### How To: Find the formula of a given sequence

In this tutorial, we learn how to find the formula of a given sequence. First, you need to decide what you're starting with. Start with a1, then continue on with a2, a3, and a4. Eventually, you will have an "An". You will have an "n" in your numerator and the denominator will start between the numbers of your fractions. Look to see if that works, then you have to see where the signs alternate on the fractions. Write in any negatives that you have, then figure your power out. Once you follow t...

### How To: Write a slope-intercept equation given an X-Y table

In this tutorial the author shows how to derive a slope-intercept equation of a line given an X-Y table. He explains that the general form of slope intercept form which is y = m*x + b. Now he intends to find value of slope, i.e. m first. Now slope is change in y over change in x. He computes the slope using the X-Y values from the table. Next he substitutes a pair of x, y value in the equation to compute the value of y intercept b. Now finally substituting the values in the equation the slop-...

### How To: Spend Money on a Graphing Calculator? Nah—Just Use This Web-Based TI Emulator

For the majority of my math classes in middle and high school, a graphing calculator was a must. While the calculators were very useful to have, they were quite steep in the price column. After losing the TI-83 graphing calculator my parents bought me in high school, I had to save up my own money to buy the next one.

### How To: Find the area of irregular shapes

This video explains how to find the area of irregular shapes. Draw the shape on a grid or graph paper. This will help you divide your shape into pieces. Draw dotted lines to divide the shape into squares, rectangles or triangles. For instance, if you have an "L" shape, you can divide the shape into two rectangles. Be sure your shapes do not overlap. Calculate the area of each individual shape. The graph paper will help you determine the length and width of each shape. Add the resulting areas ...

### How To: Minimize the sum of squared error for a regression line in statistics

Learn how to minimize the sum of squared error for regression line problems in stats. Whether you need help studying for that next big stats text or just a hand finishing your homework, you're sure to be well served by this four-part free video math lesson from Salman Khan.

### How To: Solve an equation with fractional powers

Solving equations involving fractional powers of a variable are not that hard to solve as they sound. In fact, just watch this video to learn a few tips and solving these type of equations will become a little bit easier.