Answer:
(x + 6y)(x - 3y)
Step-by-step explanation:
Given
x² + 3xy - 18y²
Consider the factors of the coefficient of the y² term (- 18) which sum to give the coefficient of the xy- term (+ 3)
The factors are + 6 and - 3 , since
6 × - 3 = - 18 and 6 - 3 = + 3 , then
x² + 3xy - 18y² = (x + 6y)(x - 3y)
