Factor by grouping sometimes called the acmethod 11x2 2x 9

Factor by grouping (sometimes called the ac-method). 11x^2 + 2x - 9 First, choose a form with appropriate signs. Then, fill in the blanks with numbers to be used for group. Finally, show the factorization. Form: 11x^2 + x + x - 9 11x^2 + x - x - 9 11x^2 - x + x - 9 11x^2 - x - x - 9

Solution

given f(x) = 11x^2 + 2x - 9

= 11x^2 + 11x - 9x - 9

= 11x(x+1) -9(x+1)

= (x+1)(11x-9)

for factors f\'(x) = 0

  (x+1)(11x-9) = 0

x =- 1 and x=9/11