Question

Use substitution to solve the system of equations.

{3x = 6y + 12
{18y = 9x -32

A. (2, -1)
B. (38/9, 1/9)
C. (6, 1)
D. No solution (I think it's this one)

Answer 1

(x,y) plug the number that corresponds to x and y into the equation. For example, answer A has (2,-1), so plug in 2 for x and -1 for y into your equation.

Answer 2

Does that make sense to you?

Answer 3

So, would it be A because:
3x = 6y + 12
3(2) = 6(-1) + 12
6 = 6

Answer 4

Yes, it does work for the first equation, but it should also work for the second equation for it to be right.

Answer 5

If I plug it into the second equation I get:
18y = 9x - 32
18(-1) = 9(2) - 32
-18 = 18 - 32
-18 = -14

so A is not right.

Answer 6

you got it. You have to do the same for the other values until you find a (x,y) that works in both. If you cannot find one that works for both, then the answer would be no solution.

Answer 7

I did C and it doesn't work either, but I'm not sure how to do B because it's fractions. Can you help?

Answer 8

I would use a calculator since the point of this problem is to learn to do system of equations, not to learn fractions.

Answer 9

It sounds like you understand system of equations since you worked out A and C to be false. So, your initial guess of no solution was right.