5(u+3)(-u+6)=0

Solution for 5(u+3)(-u+6)=0 equation:

5(u+3)(-u+6)=0

We add all the numbers together, and all the variables

5(u+3)(-1u+6)=0

We multiply parentheses ..

5(-1u^2+6u-3u+18)=0

We multiply parentheses

-5u^2+30u-15u+90=0

We add all the numbers together, and all the variables

-5u^2+15u+90=0

a = -5; b = 15; c = +90;
Δ = b2-4ac
Δ = 152-4·(-5)·90
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{-(15)-45}{2*-5}=\frac{-60}{-10}
=+6
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+45}{2*-5}=\frac{30}{-10}
=-3
$