12x2-15x=3(4x+15x)

Solution for 12x2-15x=3(4x+15x) equation:

12x^2-15x=3(4x+15x)

We move all terms to the left:

12x^2-15x-(3(4x+15x))=0

We add all the numbers together, and all the variables

12x^2-15x-(3(+19x))=0


We calculate terms in parentheses: -(3(+19x)), so:

3(+19x)

We multiply parentheses

57x

Back to the equation:

-(57x)


We add all the numbers together, and all the variables

12x^2-72x=0

a = 12; b = -72; c = 0;
Δ = b2-4ac
Δ = -722-4·12·0
Δ = 5184
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5184}=72$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-72)-72}{2*12}=\frac{0}{24}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-72)+72}{2*12}=\frac{144}{24}
=6
$