sparra sparra 09-05-2021 Mathematics contestada 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