Question

Which equation is a quadratic equation?
Answer
y + 3 = 5x + 10
y + 4x^2 = (4x - 2)(x + 3)
y - 8x = (x^2 + 1)(9x - 7)
y = 2x + 7x(x + 1)

Answer 1

expand all and see whether which one has the highest degree of x^2

Answer 2

isnt there a simpler way to see if the equation is quadratic?

Answer 3

yes

Answer 4

you realize that in y = 2x + 7x(x + 1) , you expand it you'll get x^2

Answer 5

yea

Answer 6

others like
y - 8x = (x^2 + 1)(9x - 7)
y + 3 = 5x + 10
y + 4x^2 = (4x - 2)(x + 3)
will give you x^3 or x^4 so that's incorrect

Answer 7

you want quadratic, so, y = 2x + 7x(x + 1) expanded you'll get a quadratic

Answer 8

k thanks