It is asked factorise (not asked only factors)
4x^2 – 20x + 25
product of coefficient of 1st and 3rd term = 4 × 25 = 100
Find the factors of 100 such that their sum or difference is coefficient of middle term.
100 = 10 × 10 and 10 + 10 = 20
But we want – 20 and (– 10 – 10 ) = – 20
4x^2 – 20x + 25
= 4x^2 – 10x – 10 x + 25
= 2 x (2x – 5) – 5 (2x – 5)
= (2x – 5)(2x – 5)
it's not the diference of two squares......a^2 + 2ab + b^2 = (a+b)^2 the diference between 2 squares is a^2 - b^2 = (a-b)(a+b) and yes....the answer is (2x-5)^2