4b(b=5)

Solution for 4b(b=5) equation:

4b(b=5)

We move all terms to the left:

4b(b-(5))=0

We multiply parentheses

4b^2-20b=0

a = 4; b = -20; c = 0;
Δ = b2-4ac
Δ = -202-4·4·0
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$b_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-20)-20}{2*4}=\frac{0}{8}
=0
$
$b_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-20)+20}{2*4}=\frac{40}{8}
=5
$