-x^2+15x-11=0

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

-x^2+15x-11=0

We add all the numbers together, and all the variables

-1x^2+15x-11=0

a = -1; b = 15; c = -11;
Δ = b2-4ac
Δ = 152-4·(-1)·(-11)
Δ = 181
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-\sqrt{181}}{2*-1}=\frac{-15-\sqrt{181}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+\sqrt{181}}{2*-1}=\frac{-15+\sqrt{181}}{-2}
$