X(x+6)=18.3

Solution for X(x+6)=18.3 equation:

X(X+6)=18.3

We move all terms to the left:

X(X+6)-(18.3)=0

We add all the numbers together, and all the variables

X(X+6)-18.3=0

We multiply parentheses

X^2+6X-18.3=0

a = 1; b = 6; c = -18.3;
Δ = b2-4ac
Δ = 62-4·1·(-18.3)
Δ = 109.2
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{-(6)-\sqrt{109.2}}{2*1}=\frac{-6-\sqrt{109.2}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(6)+\sqrt{109.2}}{2*1}=\frac{-6+\sqrt{109.2}}{2}
$