Question

Which of the following expressions are perfect-square trinomials? a. x² – 16x – 64 b. 4x² +12x + 9 c. x² + 20x + 100 d. x² + 4x + 16

Answer 1

c

Explanation:

A perfect square trinomial has the form

(x + b)² , (x - b)²

expand using FOIL

(x + b)²

= x² + 2bx + b²

where the coefficient of the x- term is twice the factor of b

c : x² + 20x + 100

= x² + 20x + 10² ( 20 = 2 × 10 )

= (x + 10)² ← a perfect square