-5(u-8)(-u-1)=0

Solution for -5(u-8)(-u-1)=0 equation:

-5(u-8)(-u-1)=0

We add all the numbers together, and all the variables

-5(u-8)(-1u-1)=0

We multiply parentheses ..

-5(-1u^2-1u+8u+8)=0

We multiply parentheses

5u^2+5u-40u-40=0

We add all the numbers together, and all the variables

5u^2-35u-40=0

a = 5; b = -35; c = -40;
Δ = b2-4ac
Δ = -352-4·5·(-40)
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-35)-45}{2*5}=\frac{-10}{10}
=-1
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-35)+45}{2*5}=\frac{80}{10}
=8
$