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

Solution for (4-u)(5u+6)=0 equation:

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

We add all the numbers together, and all the variables

(-1u+4)(5u+6)=0

We multiply parentheses ..

(-5u^2-6u+20u+24)=0

We get rid of parentheses

-5u^2-6u+20u+24=0

We add all the numbers together, and all the variables

-5u^2+14u+24=0

a = -5; b = 14; c = +24;
Δ = b2-4ac
Δ = 142-4·(-5)·24
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(14)-26}{2*-5}=\frac{-40}{-10}
=+4
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(14)+26}{2*-5}=\frac{12}{-10}
=-1+1/5
$