x(x+4)=7,221

Solution for x(x+4)=7,221 equation:

x(x+4)=7.221

We move all terms to the left:

x(x+4)-(7.221)=0

We add all the numbers together, and all the variables

x(x+4)-7.221=0

We multiply parentheses

x^2+4x-7.221=0

a = 1; b = 4; c = -7.221;
Δ = b2-4ac
Δ = 42-4·1·(-7.221)
Δ = 44.884
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{-(4)-\sqrt{44.884}}{2*1}=\frac{-4-\sqrt{44.884}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+\sqrt{44.884}}{2*1}=\frac{-4+\sqrt{44.884}}{2}
$