(2x-7))6x+9)

Answer 1

your brackets don't match, the number of left and right brackets should be equal.

did you mean
(((2x-7))6x+9) ?
then
12x^2 - 42x + 9 is your final expression.

Answer 2

(2x-7)(6x+9)
12x^2+18x-42x-63
12x^2-24x-63