Question

What is the factored form of the following expression?

W^2 + 18w + 77

Answer 1

`\large\boxed{w^2+18w+77=(w+11)(w+7)}`

Explanation:

`w^2+18w+77\\\\77=7\cdot11\\18=7+11\\\\w^2+18w+77=w^2+11w+7w+77=w(w+11)+7(w+11)\\\\=(w+11)(w+7)`

Other method:

`\text{Use:}\ (a+b)^2=a^2+2ab+b^2\\\\w^2+18w+77=0\qquad\text{subtract 77 from both sides}\\\\w^2+18w=-77\\\\w^2+2(w)(9)=-77\qquad\text{add}\ 9^2\ \text{to both sides}\\\\w^2+2(x)(9)+9^2=-77+9^2\\\\(w+9)^2=-77+81\\\\(w+9)^2=4\to w+9=\pm\sqrt4\\\\w+9=-2\ \vee\ w+9=2\qquad\text{subtract 9 from both sides}\\\\w=-11\ \vee\ w=-7\\\\(w-(-11))(w-(-7))=(w+11)(w+7)`

Answer 2

(w + 11)(w + 7)

Explanation:

Consider the factors of the constant term ( + 77) which sum to give the coefficient of the w- term ( + 18)

The factors are + 11 and + 7, since

11 × 7 = 77 and + 11 + 7 = + 18

w² + 18w + 77 = (w + 11)(w + 7)