(4+x)(x=18)

Solution for (4+x)(x=18) equation:

(4+x)(x=18)

We move all terms to the left:

(4+x)(x-(18))=0

We add all the numbers together, and all the variables

(x+4)(x-18)=0

We multiply parentheses ..

(+x^2-18x+4x-72)=0

We get rid of parentheses

x^2-18x+4x-72=0

We add all the numbers together, and all the variables

x^2-14x-72=0

a = 1; b = -14; c = -72;
Δ = b2-4ac
Δ = -142-4·1·(-72)
Δ = 484
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{484}=22$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-22}{2*1}=\frac{-8}{2}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+22}{2*1}=\frac{36}{2}
=18
$