Question

Can someone explain the changing of the signs on both side of the equation?

Answer 1

The whole equation is multiply my -1.

-2x2 + 5x + 5 = 0

Now multiply it with -1.

-1 (-2x2 + 5x + 5 = 0) and you get:

2x2 - 5x - 5 = 0.

It doesn't matter the answer will be the same.