Question

How do you factor the trinomial `4a^2 − 20a + 25`?

Answer 1

It is

`4a^2 − 20a + 25=(2a)^2-2*(2a)*5+5^2=(2*a-5)^2`

Note we used the identity `x^2-2*x*y+y^2=(x-y)^2`