(9-u)(5u-6)=0

Solution for (9-u)(5u-6)=0 equation:

(9-u)(5u-6)=0

We add all the numbers together, and all the variables

(-1u+9)(5u-6)=0

We multiply parentheses ..

(-5u^2+6u+45u-54)=0

We get rid of parentheses

-5u^2+6u+45u-54=0

We add all the numbers together, and all the variables

-5u^2+51u-54=0

a = -5; b = 51; c = -54;
Δ = b2-4ac
Δ = 512-4·(-5)·(-54)
Δ = 1521
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1521}=39$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(51)-39}{2*-5}=\frac{-90}{-10}
=+9
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(51)+39}{2*-5}=\frac{-12}{-10}
=1+1/5
$