How to calculate the square of 2A + 5A + 3 = 0?

How to calculate the square of 2A + 5A + 3 = 0?

2a^2+5a+3=0
(2a+3)(a+1)=0
2A + 3 = 0 or a + 1 = 0
therefore
A = - 3 / 2 or - 1