Question

which equation is a quadratic equation
a.y + 7 = -3x(4 - x) + 9x,
b.y = -2x + 5,
c.y + 2x3 = (2x - 2)(x + 5),
d.y - 9x = (x2 + 1)(5x - 1) + 3

Answer 1

Its a, you can see that when you expand all the terms , you'll get the highest degree of 2
(which is quadratic)
y + 7 = -3x(4 - x) + 9x

Answer 2

thank you