4.

Factor the expression.

4b2 + 28b + 49

(2b − 7)2

(−2b − 7)2

(2b + 7)2

(−2b + 7)2

1 answer

To factor the expression \(4b^2 + 28b + 49\), we should look for a pattern or use factoring techniques. In this case, notice that the expression resembles a perfect square trinomial. A perfect square trinomial is of the form \((ax + b)^2\).

Let's consider:
\[ 4b^2 + 28b + 49 \]

We can rewrite the middle term (28b) as twice the product of the square root of the first term (\(4b^2\)) and the square root of the third term (\(49\)):
\[ 4b^2 + 28b + 49 = (2b)^2 + 2(2b)(7) + 7^2 \]

Recognizing that this matches the form \((a x + b)^2\), we can see that:
\[ 4b^2 + 28b + 49 = (2b + 7)^2 \]

Thus, the factorization of the expression is:
\[ (2b + 7)^2 \]

Therefore, the correct factorization from the given options is:
\[ \boxed{(2b + 7)^2} \]