Perfect square trinomials are in the form (a+b)^2 = a^2+2ab+b^2
So the first and last terms must be perfect squares. The middle term is twice that of the square roots of each first and last term.
Choice D fits the description because 4x^2 = (2x)^2 is the first term, so a = 2x and 25 = 5^2 is the last term meaning b = 5. Note how 2ab = 2*2x*5 = 20x is the middle term.
(2x + 5 )(2x + 5 ) the constant sign is plus so it can be ( minus × minus=plus OR plus×plus=plus) look at the middle value it is positive so the two signs are positive or plus sign.
