I’m very confused at when i can and cant put the - inbetween the braquets when im squaring a number. Here’s the problem im working on: Solve g(x) = -1/10x^2 + 2x - 1,9 using the abc-formula.

These are the steps i took:

g(x) = -1/10x^2 + 2x - 1,9

-1/10x^2 + 2x - 1,9 = 0

x^2 - 20x + 19 = 0

This is when i need to use the abc-formula, which is

The letters a, b and c in the abc-formula are the same as in ax^2 + bx + c. In this case it is x^2 - 20x + 19 = 0.

Hower i dont really know if b=20 or b=-20. And if b=-20, does that become -b = 20 in the abc formula? If that makes sense. It is difficult to understand all these little rules. I hope my question made sense.