Question

Use substitution to solve.

2x² = 5 + y
4y = -20 + 8x²

Solve the first equation for y and substitute it into the second equation. The resulting equation is
.

Answer 1

From 2x² = 5 + y we get y = 2x² − 5. Substitute into the second:

4(2x² − 5) = −20 + 8x²

So the resulting equation is 8x² − 20 = −20 + 8x², which simplifies to 0 = 0. Thus every (x, y) with y = 2x² − 5 is a solution.