# Hot Math Posts  ### How To: Find the standard deviation with the Z-Score formula

In this tutorial, we learn how to find the standard deviation with the Z-Score formula. First, take your problem and write it out one by one underneath each other. Then, you will need to substitute the numbers in for the variables that are in the problem. Once you do this, you will follow the basic rules of math to find out what the answer to the problem is appropriately. Once you have done this, finish off the problem to find the answer, then you will have found the standard deviation using ... ### How To: Find and sketch the domain of a multivariable function

Looking for a primer on how to find and sketch the domain of a function z = f(x, y) in calculus? Learn how with this free video calc 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: 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 circular velocity & acceleration

In this video the tutors explain about the concepts of Circular Velocity and Acceleration. She explains the concepts using a real world small experiments. She shows that the equation to calculate circular velocity is v = (2 * Pi * r) / T, where r is the radius of the circle the object moves in, and T being its time period. Now she takes the values from the experiment and calculates the velocity of the other tutor who is the object that runs around in the circle for the experiment. She even co... ### How To: Find density using the water displacement method

To find out the density of any given object there is a simple equation, mass divided by the volume equals the density. In this video a lady is showing how to get the volume of three objects using water. First the objects are measured on a scale to find out how much they weigh, the mass. Next each one of the objects is placed into a measured amount of water to find out the volume. Before you place the object into the water you will want to know just how much water in there. That way when the o... ### How To: Find the equation of an ellipse given a graph

Notes College Algebra teaches you how to find the equation of an ellipse given a graph. You first want to find out the center of the ellipse, which in the video is (2, -3). The major axis is parallel to the X axis. The equation is (x - h) squared/a squared plus (y - k) squared/a squared equals 1. A is the distance from the center to either of the vertices, which is 5 over here. B is the distance from the center to the top or bottom of the ellipse, which is 3. You then use these values to find... ### 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: Compute a square root using the geometric method

With mathematics, as with anything else, not everyone progresses at the same rate. Happily, in the age of Internet video tutorials, this isn't a problem. Those who progress quickly can go beyond what's being taught them and those who are struggling likewise have all the time in the world to catch up. With this free video math lesson, you'll learn how to calculate the value of a square using using geometry. ### 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: Find the equation for a growth pattern

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 find an equation that describse the growth pattern of a sequence of blocks. ### How To: Solve word problems involving mixtures

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 word problems involving a mixture of two or more substances. ### How To: Clear decimals from a linear equation

Need instructions on how to remove decimal values from a linear equation in algebra? 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: Prove Rank(A) = Rank(transpose of A) in linear algebra

Learn how to prove that the rank of a matrix, A, is equal to the rank of its transpose in linear algebra. 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: Graph a linear equation

In this video tutorial, viewers learn how to graph a linear equation. The linear equations example used in this video is y= 1/3x-3. The equation to graph a linear equation is y= mx+b. Now substitute each number into the equation. Therefore, m= 1/3 and b= -3. Begin by graphing the Y-intercept. M is the slope and b is the y-intercept. Plot the y-intercept on the -3 axis. Then move up once and to the side 3 times. This video will benefit those viewers who are struggling with this math unit and a... ### 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: Factor a trinomial with negative leading coefficient

In this video the instructor shows how to factor a trinomial with negative leading coefficient. Most of the students are confused when they have to factor a trinomial with a negative leading coefficient. But there are many ways to solve these kind of problems as shown in this video. One way you can do is that take out the greatest common factor (GCF) of -1 from the equation. So pulling the -1 gives you the original trinomial with all the signs of the terms changed. Now go on and factor the ne... ### How To: Find the vertices of a polygon of constraints

In this tutorial the instructor shows how to find the vertices of a polygon of constraints. In any optimization problem after defining your polygon you need to find its vertices. First you will have a set of equations which represents the constraints in your problem. Now you have to find the coordinates of the vertex of it by solving the optimization problem. To do that you have to start with a point and check the lines that are passing through it. Now take those lines and solve them for the ... ### How To: Graph by using an X-Y table

In this video the author shows how to graph using an X-Y table. He shows how to do this with a sample equation. He builds a table of x, y values where he takes sample values for x like -1, 0, 1 and now he substitutes these values in the equation of the line and obtains the corresponding y values. Now finally he has an x, y value table which now he shows how to plot it on a coordinate plane. He plots all the three pairs on the graph and connects them with a line finally obtaining the resultant... ### How To: Use the TOA formula in trigonometry

The video is a tutorial in trigonometry. The teacher teaches that the tangent or the tan of an angle is the ratio of the opposite side to the adjacent side of a right angled triangle. If one side and one angle is given then the value of the unknown side can be found by solving the equation tan of angle is equal to opposite upon adjacent side. If the angle is to be found then the tan inverse of the value is seen in the calculator. ### How To: Calculate square roots on paper the easy way

Perhaps not as easy as using a calculator, but easy nevertheless! With mathematics, as with anything else, not everyone progresses at the same rate. Happily, in the age of Internet video tutorials, this isn't a problem. Those who progress quickly can go beyond what's being taught them and those who are struggling likewise have all the time in the world to catch up. With this free video math lesson, you'll learn how to find square roots by hand. ### How To: Multiply and simplify square roots

In this tutorial we learn how to multiply and simplify square roots. When you multiply square roots, you will first need to put them under one radical. From here, you will need to factor out what you have. Once you find a perfect square, find the square root of it. You can either write these as all separate equations or pull the perfect root on the outside of the other parts of the equation. Do the math until you find what you are left with. From here, you can do basic math to find what's lef... ### How To: Find abc, curve direction & y-intercept (quadratic eq)

In this tutorial, we learn how to find abc, curve direction & y-intercept (quadratic eq). First, you need to find the a,b, and c of the equation. A will equal what the coefficient is in the equation, B will equal the second, and C will equal the third term. This tells us if the numbers are positive or negative, so so know if the parabola opens up or down. To graph C, you will know what the y-intercept is going to be, then find the matching units. After this, you will use B to shape the parabo... ### How To: Express a ratio as a fraction in simplest form

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 rewrite a ratio as a fraction in its simplest form. ### How To: Use interval notation to express inequalities

Could you use a little help figuring out how to use interval notation to express inequalties? 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 give inequalities in interval nota... ### How To: Figure out the domain of a vector function

Need to know how to calculate the domain of a vector-valued 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: Solve quadratic equations by factoring

This is a great educational video on how to solve quadratic equations by factoring. Let us take an example and try to learn the method. Here is a quadratic equation: (r+7) (r-9) = 0. Consider zero-factor property. For real a and b, if a.b = 0, then a = 0 or b = 0 or both are equal to zero. So r+7 = 0 or r-9 = 0 > r = -7 or r = 9. Hence, r = -7, 9. Similarly to solve a quadratic equation (13r+7) (6r-18) = 0, we will get 13r = -7 or r = -7 over 13. Also 6r = 18 or r = 3. So r= -7over 13, 3. Thi... ### How To: Solve quadratic equations by square root method

In this video the instructor shows how to solve quadratic equation by the square root method. The square root property of equations states that if k is positive and a*a = k, then a is equal to square root of k or -1 times the square root of k. So to solve a quadratic equation by square root property first get the equation in the form of a*a = k. Now apply the square root property explained in the previous step to get the result. The instructor now demonstrates these concepts by solving some e... ### How To: Do Celsius to Fahrenheit temperature conversion

The video teaches how to convert degrees Celsius to degrees Fahrenheit. First the boiling points of 32 degrees Fahrenheit and 100 degrees Celsius are plotted on the Y and X axis. Then a line is drawn to join them both. The value m is delta Y (boiling point minus freezing point, i.e., 212-32)/ delta X (boiling point minus freezing point, i.e., 100-0). So m works out to 180/100 or 1.8. Then the formula y=mx+b (intercept of y = 32) is used, substituting X with Celsius and y with Fahrenheit, to c... ### How To: Graph an inequality on a number line in Algebra

The video described here from [free math tutoring Freemathtutoring] teaches how to plot natural number on a number line in different situations. First, the author defines natural numbers, integers and real numbers. He then teaches different methods on how to plot natural numbers on a number line. The most important fact to remember is that natural numbers are greater than 0; they do not include negative numbers. Like wise, he explains different situations to plot natural numbers on a number l... ### How To: Find the surface area of a rectangular prism

Have a 3 dimensional figure that you can not figure out the surface area? This video teaches the fundamental concepts and techniques of figuring out the surface area of a 3 dimension figure. In this video, the specific shape will be a rectangular prism. The video will assist its viewers in understanding and learning the process of how to find the surface area of this 3 dimensional figure. The method is simple and easy to learn. This is highly recommended to anyone with an interest in math. ### How To: Find the volume of a rectangular prism quickly

In this video, you will see the steps for finding the volume of a rectangular prism written on a white board. The steps are labeled along the right side. A blue cursor boxes the steps as they are introduced on the board. The formula for finding volume is written along the top left. Colored arrows point out the measurements. Each step is presented in a colored format so it is easy to follow the steps. The final answer is circled in yellow so it is a cinch to compare your answer with the correc... ### How To: Convert to a higher equivalent fraction

A representative from Math Problem Generator explains in this video that converting a simple fraction from its current state to a higher equivalent can be very simple. He explains the process neatly and provides a great example. To convert a fraction, you must multiply the numerator and the denominator by the exact same number. The example he shows is captured from the screen of a computer and is written out in some sort of a painting program. The example shows that four-ninths equals eight-e... ### How To: Use the ratio formula to find coordinates of a point

This video is recorded in a mathematics class room. It is very clear by the sound and picture. The faculty here is explaining that the ratio between two numbers can be found using various formulae and methods. For example, 3:1 is the ratio between p and q. Likewise he explained the other formulae and methods.