Hot Math Posts

How To: Find the volume of a sphere with radius r

Are you slightly rusty on your math skills? This video demonstrates how to find the volume of a sphere with a given radius. The first step is to sketch a solid and cross-sectional view of your sphere to get an understanding of the process to come. Next, find a formula for the area of this cross-section. Third, find the limits of integration. This will allow you to take the area of each cross-section in the sphere, not just the singular one you are viewing. Lastly, integrate this formula from ...

How To: Compare exponential expressions

In this video the tutor shows how to compare exponential expressions and judge if they are equivalent. He shows how to do this using examples to simply exponential expressions. Now after simplifying the numerator and denominator separately he reduces the fraction to arrive at a simple value. Now using this simple values we can compare them and judge if both their values are equivalent. This video gives a good introduction on how to simplify the exponential expression and how to compare them a...

How To: Find slant (oblique) asymptotes of rational functions

In this educational video the instructor shows how to find the slant asymptotes of rational functions. Slant or oblique asymptotes occur when the degree of the numerator is exactly one greater than the degree of the denominator of the rational function. The way to find the equation of the slant asymptote from the function is through long division. In this long division you divide the numerator with the denominator by following the long division method as shown in this video. Before dividing i...

How To: Solve & find the least common multiple

This is a mathematical instructional video on how to find the least common multiple. Let us now find the least common multiple for 25, 100, 18. This can be written as 5 square, 2 square multiplied by 5 square, 2 multiplied by 3 square. The highest factor in these numbers are, 5 square, 2 square and square. If you multiply 5 square with 2 square and 3 square you will get the final answer as 900. This is the least common multiple of 25, 100, and 18. This method is explained very clearly in this...

How To: Solve multi-step equations with absolute values

This educational math video describes the steps necessary to solve an equation involving absolute values. "Absolute value" refers to the magnitude of a quantity and is always expressed as a positive number. You can think of absolute value as the distance a number would be from zero if plotted on a number line. Positive 17 and negative 17 both have the same absolute value because both are 17 units from zero on a number line. Because of this, all absolute value problems have two answers, one wh...

How To: Calculate the area of a parallelogram

Calculating The Area Of A Parallelogram A parallelogram is a 4-sided shape formed by two pairs of parallel lines. Opposite sides are equal in length and opposite angles are equal in measure. To find the area of a parallelogram, multiply the base by the height. The formula is:

How To: Calculate the area of complex shapes

Watch this video to learn how to calculate the area inside complex figures--shapes composed of multiple smaller, simpler shapes. The first step is to break the shape into its simpler component shapes. Then, using the information you have about the large shape, find all information you can about the smaller ones: base, height, etc. Next, find the areas of the smaller component shapes. Finally, add the areas of each of the component shapes together to find the area of the complex shape. Now you...

How To: Simplify a quadratic formula result

In this video the tutor shows how to simplify a quadratic formula result. You can solve a quadratic equation using the quadratic formula. The first thing you have to do when given the quadratic equation is bring all the terms to one side so that you have a zero on the other side of the equals to sign. Now the formula to calculate the roots of the quadratic equation ax*x + bx + c = 0 is x = (-b + root of(b*b - 4*a*c) ) / 2 * a. The other root can be obtained by using the minus sign before the ...

How To: Factor trinomials with the "swing method"

This is a very interesting educational video on how to find the factor trinomials using the swing method. Let us take an example and find the factor trinomials for 2xsquare-13x-45. Let us use the swing method. So now we will get 2xsquare -13x-45. You have to find the suitable factors of 90. It is 18 and 5. If you multiply 18 by 5 you will get 90. You will get (x-18over2)(x+5over2). The final answer is (x-9)(2x+5). Now we have found out the factor trinomials of 2xsquare-13x-45. This swing meth...

How To: Find the equation of a line given 2 points

This tutorial teaches you how to find a mathematical equation of a line given 2 points that exists on the line. The tutorial starts off with 2 points labeled (2,-4) and (3,6). The first step is to determine the slope of the line using the formula given in the tutorial in blue. The slope is then solved as 'm'. Plug the slope and the points into another formula given in green. The tutorial maker provides a tip that one can use x1 and y1 or x2 and y2, however, it must be consistent. After, solve...

How To: Solve percent equations

In this tutorial the instructor shows how to solve percent equations. The general form of a percent equations is that a is b% of c. As there can be three kinds of variables a, b, c, the questions involving percent equations can be of three types having one of the three variables unknown. These kind of percent statements can be solved easily by setting up an equation. So, to convert percent statement into a equation replace the unknown term with n, the 'is' term with equals sign and the '%' si...

How To: Find the circumference of a circle

Use a simple mathematical formula to find the circumference of a circle. The circumference of a circle can be determined by using the formula 2 times pi times the circle's radius. Pi is equal to 3.14. If a circle's radius is 10 centimeters, first multiply pi times 2. Pi, or 3.14, times 2 is 6.28. The next step then is to multiply 6.28 times the circle's radius. Since the circle's radius is 10 centimeters, multiply it by 6.28. This gives you 60.28. 60.28 inches, then, is the circumference of t...

How To: Find the x & y intercepts of rational functions

In this tutorial the instructor shows how to find the x and y intercepts of rational functions. Finding the intercepts of a rational function is similar to finding the intercepts of other normal equations. You can find the x intercept of the equation by setting the value of y to zero and solving the equation. Similarly you can solve the y intercept by setting the value of x to zero and solving the equation. Now while solving this rational function for intercepts if you face a situation where ...

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: Find the vertical asymptotes of rational functions

To find a vertical asymptote, you are trying to find values of x that produce 0 in the denominator but not in the numerator. If 0/0 occurs, that means you have a "hole" in the graph. A vertical asymptote is a place in the graph of infinite discontinuity, where the graph spikes off to positive or negative infinity. To find the vertical asymptote, set the denominator equal to zero and solve for x. Check that the values also do not give a zero in the nominator. If the values work, you have found...

How To: Find the 100th term in a sequence

Need to find the nth term in a given arithmetic sequence? See how it's done with this free video math lesson. Need help finding the 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 seri...

How To: Use vertex formula to find the vertex of a parabola

Looking for a guide on how to find the vertex of a parabola using the vertex formula? Learn how with this free video algebra 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).

How To: Figure out the domain & range of a piecewise function

Need to calculate the domain and range of a graphed piecewise function? Learn how with 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).

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: 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: Find the area of a triangle when given 2 sides & angle

This video shows you how to easily find the area of a triangle when you know the length of 2 sides and the angle between them. The first thing you have to do is mark the sides of the triangle by a, b, c, where a is the side between A and B, b is the side between B and C and c is the side between C and A. If you know 2 of these 3 sides an you know the angle between them you can find the area of the triangle very simple: Area= (a x b x sin c)/2, where a, b are the two sides and c is the angle b...

How To: Subtract mixed numbers with borrowing

This video teaches you to subtract mixed numbers with borrowing. Consider 2 mixed numbers. For example 8 and 2/7 and the other 5 and 4/5.You have to subtract 5 and 4/5 from 8 and 2/7. First you have to convert the fractions to their common denominator. To equate the denominators of these two fractions you have to multiply the first denominator with the numerator and the denominator of the second fraction and also multiply the numerator and denominator of the first fraction with the denominato...

How To: Multiply Any Number by 11 with a Super Fast Mental Trick

Most of the time, when I’m bored during math class, I play with my calculator to satisfy my boredom. Recently, I've discovered that when multiplying any number by 11, 111, or any number similar to it, that it has a pattern (though I guess everything in math has a pattern). I don't know if this technique is original, because I didn't read anything about this. It's just mere observation. If it’s a tried and true technique, let me know.

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: Graph inequalities on a number line

In this video, we learn how to graph inequalities on a number line. Inequalities have a greater than or less than sign instead of an equal signs. Remember that these are no different than figuring out how to graph normal equations. First, you will need to remove the single numbers from each side of the equation. Continue to do math on the equation until you figure out what 'x' is. From here, draw the numbers on your graph and then find the number that 'x' is greater to or less than. Use an op...

How To: Rationalize square roots

In this tutorial, we learn how to rationalize square roots. You cannot have square roots in the denominator of an equation. You need to multiply so the square root goes away. You can do this by multiplying the top and bottom of the equation by the bottom denominator. From here, this will make the square root go away, so your equation will be normal numbers. After you have done this, you will have the equation answered and you will be able to simplify it to find the end answer. You can do this...

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: Calculate standard deviation with graphing calculator

This video tutorial is in the Education category which will show you how to calculate standard deviation with TI graphing calculator. First you got to enter the data in to the calculator. Go to stat and click on enter. This will edit a list. Now you type in these numbers: 50, 20, 33, 40 and 55. Then press stat and click on enter. This will bring up the 1-var stats page. Press the "2nd" button and L1, because all our data is in L1. Click on enter and you will get all the data that you will nee...

How To: Convert top heavy fractions to mixed numbers

This is a video tutorial in the Education category where you are going to learn how to convert top heavy fractions to mixed numbers. Top heavy fractions are fractions with numerators greater than denominators. Mixed numbers are combination of whole numbers and fractions. To convert 12/5, find out how many 5s are in 12. The answer is 2 and after you remove two 5s from 12, you are left with 2. So, 12/5 is equal to 2 2/5. Similarly, in 10/3, you have three 3s in 10 and you are left with 1. So, 1...

How To: Write equivalent fractions

In this tutorial, we learn how to write equivalent fractions. If you have a negative in front of the fraction, it's the same as writing the negative on the numerator or the denominator. If we would have a negative on the top and on the bottom, this would cancel both out to create a positive, which wouldn't be right. To write the fractions, simplify it. If it's already simplified, you will need to multiply the fraction. After you do this, you will finish the equation and have it written out in...

How To: Add fractions with unlike denominators

In order to add fractions that are not alike, you will need to find the lowest common denominator. This is the least common multiple of the fractions. To add 2/3 plus 1/5, you will need to find the lowest common denominator. Here, it is best to think of all of the multiples of the denominators. If it helps, make a list. For 3, it is 3, 6, 9, 12, 15, etc. For five, the multiples are 5, 15, 20, 25, etc.

How To: Simplify complex rational expressions

In order to simplify complex rational expressions, it is important to be able to find the lowest common denominator. Complex rational expressions are fractions that are divided by fractions. When you have found the lowest common denominator, then, you should multiply both fractions by the common denominator.

How To: Rewrite an addition problem as a multiplication problem in math

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 unpack and solve problems requiring you to multiply whole numbers.

How To: Know if matrices can be multiplied

In this Education video tutorial you will learn how to know if matrices can be multiplied. If the column of the first and the row of the second match, you can multiply them. For example if, matrix A has 2 rows and 3 columns (A: 2x3) and matrix B has 3 rows and 4 columns (B: 3x4), then you can multiply them. But, if A: 3x2 and B: 3x4, you cannot multiply them. The shape of the resultant matrix will be the shape of the outer numbers. For example, we saw that if A:2x3 and B :3x2, then they can b...

How To: Factor trinomials by grouping in algebra

Learn how to factor trinomials using the grouping method in this free video algebra 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 study for that next big test).