Question

Select all of the following that are quadratic equations.
3x 2 + 5x - 7 = 0
x 3 - 2x 2 + 1 = 0
2x - 1 = 0
5x 2+ 15x = 0
6x - 1 = 4x + 7
x 2 - 4x = 4x + 7

Answer 1

1 and 6 are only quadratic equations