(5a+2)(a+4)=0

Solution for (5a+2)(a+4)=0 equation:

(5a+2)(a+4)=0

We multiply parentheses ..

(+5a^2+20a+2a+8)=0

We get rid of parentheses

5a^2+20a+2a+8=0

We add all the numbers together, and all the variables

5a^2+22a+8=0

a = 5; b = 22; c = +8;
Δ = b2-4ac
Δ = 222-4·5·8
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(22)-18}{2*5}=\frac{-40}{10}
=-4
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(22)+18}{2*5}=\frac{-4}{10}
=-2/5
$