how do you use subsitution and elimination?

Question

The question is Solve the linier system using subsitution or elimination

Answer 1

You should have two equations. One will be something like x + y = 7. The other will be something like 2x - 3y = 12.

To use substitution, you set up one of the equations so you just have x = something or y = something. In the example I gave, you can subtract y from both sides of the first equation to get x = 7-y.

Then you substitute the 7-y into the second equation in the place of x. 2(7-y) - 3y = 12. Now you only have one variable, and you can solve the equation for y Once you know y, you plug it back into one of the equations to find x.

To solve with elimination, you will again have two equations. One will be something like x + y = 7. The other will be something like x - y = 1.

Place the two equations on top of each other: x + y = 7

x - y = 1

Now add straight down. 2x + 0 = 8

Now you've gotten rid of the y, so you can solve for x. 2x = 8. x = 4

Plug back into one of the equations to solve for y.