Select all of the following that are quadratic equations.

x2 - 2x = 4x + 1

x3 - 6x2 + 8 = 0

5x - 3 = 0

2x2 + 12x = 0

5x - 1 = 3x + 8

9x2 + 6x - 3 = 0

What you want to do is solve all of these so that it equals to 0 on one side. The ones that are a quadratic will have x^2

x^2 - 2x = 4x + 1

x^2 - 6x - 1 = 0

Yes this is a quadratic

x^3 - 6x^2 + 8 = 0

No this is not a quadratic because the highest power of x is to the power of 3

5x - 3 = 0

No it is not a quadratic because it does not have x^2

2x^2 + 12x = 0

Yes because there's x^2

5x - 1 = 3x + 8

2x - 9 = 0

No because no x^2

9x^2 + 6x - 3 = 0

Yes because there's x^2