(x+2)(x+4)=8+13x

Solution for (x+2)(x+4)=8+13x equation:

(x+2)(x+4)=8+13x

We move all terms to the left:

(x+2)(x+4)-(8+13x)=0

We add all the numbers together, and all the variables

(x+2)(x+4)-(13x+8)=0

We get rid of parentheses

(x+2)(x+4)-13x-8=0

We multiply parentheses ..

(+x^2+4x+2x+8)-13x-8=0

We get rid of parentheses

x^2+4x+2x-13x+8-8=0

We add all the numbers together, and all the variables

x^2-7x=0

a = 1; b = -7; c = 0;
Δ = b2-4ac
Δ = -72-4·1·0
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-7}{2*1}=\frac{0}{2}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+7}{2*1}=\frac{14}{2}
=7
$