-4(u-6)(u+3)=0

Solution for -4(u-6)(u+3)=0 equation:

-4(u-6)(u+3)=0

We multiply parentheses ..

-4(+u^2+3u-6u-18)=0

We multiply parentheses

-4u^2-12u+24u+72=0

We add all the numbers together, and all the variables

-4u^2+12u+72=0

a = -4; b = 12; c = +72;
Δ = b2-4ac
Δ = 122-4·(-4)·72
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-36}{2*-4}=\frac{-48}{-8}
=+6
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+36}{2*-4}=\frac{24}{-8}
=-3
$