(4-u)(3u+7)=0

Solution for (4-u)(3u+7)=0 equation:

(4-u)(3u+7)=0

We add all the numbers together, and all the variables

(-1u+4)(3u+7)=0

We multiply parentheses ..

(-3u^2-7u+12u+28)=0

We get rid of parentheses

-3u^2-7u+12u+28=0

We add all the numbers together, and all the variables

-3u^2+5u+28=0

a = -3; b = 5; c = +28;
Δ = b2-4ac
Δ = 52-4·(-3)·28
Δ = 361
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{361}=19$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-19}{2*-3}=\frac{-24}{-6}
=+4
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+19}{2*-3}=\frac{14}{-6}
=-2+1/3
$