Question

Solve the system using substitution. -x+y=9 and x-y=-9

Answer 1

Infinite Number of Solutions

Explanation:

Hello!

We can solve for y in the first equation, and plug that value in for y in the second equation.

Find the Equation for Y

• -x + y = 9
• y = 9 + x

Now that we know the equation for y, we can plug that in for y into the second equation to solve for x.

Solve for X

• x - y = -9
• x - (9 + x) = -9
• x - 9 - x = -9
• -9 = -9

Since the equations match, there are an infinite number of solutions.

If we take a close look at the equations, we can also see that they are the same equation, but with flipped signs.