-4(u+2)(-u-8)=0

Solution for -4(u+2)(-u-8)=0 equation:

-4(u+2)(-u-8)=0

We add all the numbers together, and all the variables

-4(u+2)(-1u-8)=0

We multiply parentheses ..

-4(-1u^2-8u-2u-16)=0

We multiply parentheses

4u^2+32u+8u+64=0

We add all the numbers together, and all the variables

4u^2+40u+64=0

a = 4; b = 40; c = +64;
Δ = b2-4ac
Δ = 402-4·4·64
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(40)-24}{2*4}=\frac{-64}{8}
=-8
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(40)+24}{2*4}=\frac{-16}{8}
=-2
$