-a2+8a-12=0

Solution for -a2+8a-12=0 equation:

-a2+8a-12=0

We add all the numbers together, and all the variables

-1a^2+8a-12=0

a = -1; b = 8; c = -12;
Δ = b2-4ac
Δ = 82-4·(-1)·(-12)
Δ = 16
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16}=4$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-4}{2*-1}=\frac{-12}{-2}
=+6
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+4}{2*-1}=\frac{-4}{-2}
=+2
$