Question

Determine which polynomial is a perfect square trinomial.

25x2 − 40x − 16
9a2 − 20a − 25
25b2 − 15b + 9
16x2 − 56x + 49

Answer 1

a perfect square trinomial
(a + b)^2 = a^2 + 2 a b + b^2
rephrasing the question ,which expression is in this format?
hint: when you square an entity it is always positive

Answer 2

16x2 − 56x + 49

Answer 3

\[16 x^2-56 x+49=(4 x-7)^2 \]