(9u+8)(9+u)=0

Solution for (9u+8)(9+u)=0 equation:

(9u+8)(9+u)=0

We add all the numbers together, and all the variables

(9u+8)(u+9)=0

We multiply parentheses ..

(+9u^2+81u+8u+72)=0

We get rid of parentheses

9u^2+81u+8u+72=0

We add all the numbers together, and all the variables

9u^2+89u+72=0

a = 9; b = 89; c = +72;
Δ = b2-4ac
Δ = 892-4·9·72
Δ = 5329
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5329}=73$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(89)-73}{2*9}=\frac{-162}{18}
=-9
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(89)+73}{2*9}=\frac{-16}{18}
=-8/9
$