(5+u)(3u+8)=0

Solution for (5+u)(3u+8)=0 equation:

(5+u)(3u+8)=0

We add all the numbers together, and all the variables

(u+5)(3u+8)=0

We multiply parentheses ..

(+3u^2+8u+15u+40)=0

We get rid of parentheses

3u^2+8u+15u+40=0

We add all the numbers together, and all the variables

3u^2+23u+40=0

a = 3; b = 23; c = +40;
Δ = b2-4ac
Δ = 232-4·3·40
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(23)-7}{2*3}=\frac{-30}{6}
=-5
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(23)+7}{2*3}=\frac{-16}{6}
=-2+2/3
$