X*(x+3)=26

Solution for X*(x+3)=26 equation:

X(X+3)=26

We move all terms to the left:

X(X+3)-(26)=0

We multiply parentheses

X^2+3X-26=0

a = 1; b = 3; c = -26;
Δ = b2-4ac
Δ = 32-4·1·(-26)
Δ = 113
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{-(3)-\sqrt{113}}{2*1}=\frac{-3-\sqrt{113}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+\sqrt{113}}{2*1}=\frac{-3+\sqrt{113}}{2}
$