The given polynomial is expressed as
(13^2+9x-4)-(12x^2-2x+6)
The first step is to open the parentheses. The negative sign outside the second parentheses will affect every term inside the parentheses. Thus, we have
13x^2 + 9x - 4 - 12x - - 2x - + 6
Recall,
- - = +
+ - = -
Thus, we have
13x^2 + 9x - 4 - 12x + 2x - 6
By collecting like terms, we have
13x^2 - 12x^2 + 9x + 2x - 4 - 6
x^2 + 11x - 10
The final answer is
x^2 + 11x - 10