-x^2+11x-13=0

Solution for -x^2+11x-13=0 equation:

-x^2+11x-13=0

We add all the numbers together, and all the variables

-1x^2+11x-13=0

a = -1; b = 11; c = -13;
Δ = b2-4ac
Δ = 112-4·(-1)·(-13)
Δ = 69
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{-(11)-\sqrt{69}}{2*-1}=\frac{-11-\sqrt{69}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(11)+\sqrt{69}}{2*-1}=\frac{-11+\sqrt{69}}{-2}
$