Question

Which equation is a quadratic equation?

A. y + 3 = 5x + 10
B. y + 4x2 = (4x − 2)(x + 3)
C. y − 8x = (x2 + 1)(9x − 7)
D. y = 2x + 7x(x + 1)

Answer 1

D

Answer 2

a quadratic equation is of degree 2
so highest power of x in it must be to (not less than two also)

y = 2x + 7x(x + 1)
y = 7x^2 + 9x
so this is a quadratic

Answer 3

thank you! :)