Question

(MID SCHOOL ALGEBRA)

can somebody explain to me from this image, why the -13x and +6 becomes +13x and -6?

Answer 1

Basically it the same as multiplying by -1
- * - = + and - * + = -

Answer 2

- (2x^2 - 13x + 6)

The above expression is in brackets and a negative sign is outside of the brackets. This means that when expanding the expression, we have to multiply each number with the negative sign (each number would switch their signs to the opposite one). Therefore, 2x^2 becomes -2x^2, -13x becomes 13x and 6 becomes -6.