2b(b=90)

Solution for 2b(b=90) equation:

2b(b=90)

We move all terms to the left:

2b(b-(90))=0

We multiply parentheses

2b^2-180b=0

a = 2; b = -180; c = 0;
Δ = b2-4ac
Δ = -1802-4·2·0
Δ = 32400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{32400}=180$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-180)-180}{2*2}=\frac{0}{4}
=0
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-180)+180}{2*2}=\frac{360}{4}
=90
$