3x+15x2=12

Solution for 3x+15x2=12 equation:

3x+15x^2=12

We move all terms to the left:

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

a = 15; b = 3; c = -12;
Δ = b2-4ac
Δ = 32-4·15·(-12)
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-27}{2*15}=\frac{-30}{30}
=-1
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+27}{2*15}=\frac{24}{30}
=4/5
$