20a(5a+2)=36

Solution for 20a(5a+2)=36 equation:

20a(5a+2)=36

We move all terms to the left:

20a(5a+2)-(36)=0

We multiply parentheses

100a^2+40a-36=0

a = 100; b = 40; c = -36;
Δ = b2-4ac
Δ = 402-4·100·(-36)
Δ = 16000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{16000}=\sqrt{1600*10}=\sqrt{1600}*\sqrt{10}=40\sqrt{10}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-40\sqrt{10}}{2*100}=\frac{-40-40\sqrt{10}}{200}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+40\sqrt{10}}{2*100}=\frac{-40+40\sqrt{10}}{200}
$