18=2(3x+6);x=1

Solution for 18=2(3x+6);x=1 equation:

18=2(3x+6)x=1

We move all terms to the left:

18-(2(3x+6)x)=0


We calculate terms in parentheses: -(2(3x+6)x), so:

2(3x+6)x

We multiply parentheses

6x^2+12x

Back to the equation:

-(6x^2+12x)


We get rid of parentheses

-6x^2-12x+18=0

a = -6; b = -12; c = +18;
Δ = b2-4ac
Δ = -122-4·(-6)·18
Δ = 576
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{576}=24$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-24}{2*-6}=\frac{-12}{-12}
=1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+24}{2*-6}=\frac{36}{-12}
=-3
$