Which equation is a quadratic equation?
A.y = 2x(5 - x) + 7x
B.y = 8x + 2
C.y + x2 = (x - 2)(x + 8)
D.y - 7x = (x2 + 1)(x - 3)

Question

Which equation is a quadratic equation?
               A.y = 2x(5 - x) + 7x
		B.y = 8x + 2
		C.y + x2 = (x - 2)(x + 8)
		D.y - 7x = (x2 + 1)(x - 3)

jim_thompson5910 · Answer

which one do you think it is?

anonymous · Answer

C? O.o

anonymous · Answer

A quadratic equation must have 2 as its highest degree. :)

jim_thompson5910 · Answer

no, here's why


y + x^2 = (x - 2)(x + 8)


y + x^2 = x^2 + 8x - 2x - 16


y = x^2 + 8x - 2x - 16 - x^2


y = 6x - 16 .... which is a linear (and NOT a quadratic) equation

anonymous · Answer

B is not (highest power of x is 1.)
C is not (x^2 cancels out.)
D is not (x^3 is present.)

anonymous · Answer

A? (:

jim_thompson5910 · Answer

yes, choice A is a quadratic equation