9514 1404 393
Answer:
a. (5x+2)(5x+2)
Explanation:
You will recognize that the first (25x^2) and last (4) terms are perfect squares. The middle term is double the product of the roots of those squares:
2(5x)(2) = 20x
This means the given expression is a perfect square trinomial, and that it is the square of (5x+2). This matches the first choice.
25x^2 +20x +4 = (5x +2)^2 = (5x +2)(5x +2)
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Generically, ...
(a +b)^2 = a^2 +2ab +b^2
Here, we have a=5x, b=2.