6x^2-8x-18=3x^2-x-12

Solution for 6x^2-8x-18=3x^2-x-12 equation:

6x^2-8x-18=3x^2-x-12

We move all terms to the left:

6x^2-8x-18-(3x^2-x-12)=0

We get rid of parentheses

6x^2-3x^2-8x+x+12-18=0

We add all the numbers together, and all the variables

3x^2-7x-6=0

a = 3; b = -7; c = -6;
Δ = b2-4ac
Δ = -72-4·3·(-6)
Δ = 121
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{121}=11$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-7)-11}{2*3}=\frac{-4}{6}
=-2/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-7)+11}{2*3}=\frac{18}{6}
=3
$