Answer:
length = x + 5
Explanation:
Given
area = x² + 8x + 15 and area = length × width
We require to factorise x² + 8x + 15
Consider the factors of the constant term (+ 15) which sum to give the coefficient of the x- term (+ 8)
The factors are + 5 and + 3, since
5 × 3 = 15 and 5 + 3 = 8, thus
x² + 8x + 15 = (x + 5)(x + 3)
x + 3 is the width, thus x + 5 is the length