0=15x^2+4x-11

Solution for 0=15x^2+4x-11 equation:

0=15x^2+4x-11

We move all terms to the left:

0-(15x^2+4x-11)=0

We add all the numbers together, and all the variables

-(15x^2+4x-11)=0

We get rid of parentheses

-15x^2-4x+11=0

a = -15; b = -4; c = +11;
Δ = b2-4ac
Δ = -42-4·(-15)·11
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-26}{2*-15}=\frac{-22}{-30}
=11/15
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+26}{2*-15}=\frac{30}{-30}
=-1
$