(X+2)(y+1)=26

Solution for (X+2)(y+1)=26 equation:

(X+2)(X+1)=26

We move all terms to the left:

(X+2)(X+1)-(26)=0

We multiply parentheses ..

(+X^2+X+2X+2)-26=0

We get rid of parentheses

X^2+X+2X+2-26=0

We add all the numbers together, and all the variables

X^2+3X-24=0

a = 1; b = 3; c = -24;
Δ = b2-4ac
Δ = 32-4·1·(-24)
Δ = 105
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{105}}{2*1}=\frac{-3-\sqrt{105}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+\sqrt{105}}{2*1}=\frac{-3+\sqrt{105}}{2}
$