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

Solution for (9+u)(5u-3)=0 equation:

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

We add all the numbers together, and all the variables

(u+9)(5u-3)=0

We multiply parentheses ..

(+5u^2-3u+45u-27)=0

We get rid of parentheses

5u^2-3u+45u-27=0

We add all the numbers together, and all the variables

5u^2+42u-27=0

a = 5; b = 42; c = -27;
Δ = b2-4ac
Δ = 422-4·5·(-27)
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(42)-48}{2*5}=\frac{-90}{10}
=-9
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(42)+48}{2*5}=\frac{6}{10}
=3/5
$