(8u+1)(9u+5)=0

Solution for (8u+1)(9u+5)=0 equation:

(8u+1)(9u+5)=0

We multiply parentheses ..

(+72u^2+40u+9u+5)=0

We get rid of parentheses

72u^2+40u+9u+5=0

We add all the numbers together, and all the variables

72u^2+49u+5=0

a = 72; b = 49; c = +5;
Δ = b2-4ac
Δ = 492-4·72·5
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$u_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(49)-31}{2*72}=\frac{-80}{144}
=-5/9
$
$u_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(49)+31}{2*72}=\frac{-18}{144}
=-1/8
$