Question

How do I solve this question?

Answer 1

This is a perfect square trnomial
(a+b)²=a²+2ab+b²
we see that a=5x and b=2

(5x)²+2(5x)(2)+2²=0
factor
(5x+2)²=0
set equal to zero
5x+2=0
5x=-2
x=-2/5