What error did zacharias make?

The equation 0 = - 2x2 5x - 3 was the quadratic formula that Zacharias used. However, he started substituting as:

Quadratic formula as x =; substitution as x

The errors he made: he mistakenly used the negative (-) and postive (+)

* - 5 should have been 5

* 52 should have been - 52

* both the numerator and the denominator should have been - 2 instead of 2