Question

Which equation is a quadratic equation?

y + 7 = −3x(4 − x) + 9x

y = −2x + 5

y + 2x3 = (2x − 2)(x + 5)

y − 9x = (x2 + 1)(5x − 1) + 3

Answer 1

If y+7 is a constant then only first eq. is a quadratic eq.

Answer 2

thank you!