Question

Identify the factors of 4x^2 + 20x + 25.
(4x + 5)(x + 5)
(4x − 5)(x − 5)
(2x + 5)(2x + 5)
(2x − 5)(2x − 5)

Answer 1

What are the factors of x^2 − 81?
(x + 9)(x − 9)
(x − 9)(x − 9)
(x + 3)(x − 27)
Prime

Answer 2

The first term, 4x^2 is the square of 2x. The last term, 25, is the square of 5.
If the middle term is 2 * 2x * 5, then this is the square of the binomial (2x + 5)^2

Answer 3

For the second problem, you have the difference of two squares.
a^2 - b^2 = (a + b)(a - b)