Question

Which equation is a quadratic equation?

A. 5x + y = −2(x + 5)
B. 3x3 − y = (3x − 2)(x + 5)
C. y + 7x = −3x(7 − 2x) + 11
D. y − 9 = (x2 + 1)(5x − 1) + 3

Answer 1

D

Answer 2

quadratic here means a polynomial whose highest power is 2
remember, when you multiply terms you add their exponents.

Answer 3

Choice A. all powers are 1 but we want a highest power of 2. so A is not it.

Answer 4

Choice B has an x^3 on the left, and it does not look like it will cancel out with anything on the right side where the highest power is 2. power of 3 is too big. B is out.

Answer 5

I know its not D or B and A doesn't work, so the only option left is C...

Answer 6

ax^2+bx+c=0 remember the formula for quadratic equations

Answer 7

Yes It is C.
if you multiply out the right hand side, you will get a highest power of 2. That is the answer.

Answer 8

thank you! :)