x(x+20)=5.50

Solution for x(x+20)=5.50 equation:

x(x+20)=5.50

We move all terms to the left:

x(x+20)-(5.50)=0

We add all the numbers together, and all the variables

x(x+20)-(5.5)=0

We add all the numbers together, and all the variables

x(x+20)-5.5=0

We multiply parentheses

x^2+20x-5.5=0

a = 1; b = 20; c = -5.5;
Δ = b2-4ac
Δ = 202-4·1·(-5.5)
Δ = 422
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-\sqrt{422}}{2*1}=\frac{-20-\sqrt{422}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+\sqrt{422}}{2*1}=\frac{-20+\sqrt{422}}{2}
$