How to Do Substitution in Math With Both Y Values
Follow

Pin

Share


Share

Email
Next Video:
How to Work on PEMDAS in PreAlgebra....5
Substitution is one of the methods used to solve a system of equations which is used to solve for where two lines actually meet. Find out how to do substitution in math with both Y values with help from an experienced mathematics professional in this free video clip.
Promoted By Zergnet
Video Transcript
Hi, I'm Drew Moyer, and this is how to do substitution in math with both Y values. Substitution is one of the methods used to solve a system of equations which is used to solve for where two lines actually meet. So if I'm given two equations, I can use this method to find out the point at which they intersect. Let's say I have these two equations, Y equals 3X minus 5 and Y equals negative 1/2X plus 2. Now substitution involves the principle that if both of these things are equal to Y then they must also be equal to each other. So I will set them equal to each other like this, 1/2X plus 2 and now you can see I have only one variable which I can solve for. So I'm going to multiply everything by 2 to get rid of this fraction, 6X minus 10 equals negative X plus 4, then I will bring this X over to this side by adding it, 7X minus 10 equals 4 and then I will add 10 to both sides, 7X equals 14. Lastly I will divide both sides by 7, X equals 2. So now I have one half of the things I am looking for. I have an X coordinate. To get my Y coordinate, all I'll have to do is plug this value back into either of the two equations and solve for Y. So I will pick the first one, Y equals 3 times the quantity 2 minus 5, Y equals 6 minus 5, Y equals 1. So the answer to this system of equations is 2, 1 and that will be the point that both of these lines intersect. I'm Drew Moyer and this is how to do substitution in math with both Y values.