-2(x-3)(x-11)=0

Solution for -2(x-3)(x-11)=0 equation:

-2(x-3)(x-11)=0

We multiply parentheses ..

-2(+x^2-11x-3x+33)=0

We multiply parentheses

-2x^2+22x+6x-66=0

We add all the numbers together, and all the variables

-2x^2+28x-66=0

a = -2; b = 28; c = -66;
Δ = b2-4ac
Δ = 282-4·(-2)·(-66)
Δ = 256
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{256}=16$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-16}{2*-2}=\frac{-44}{-4}
=+11
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+16}{2*-2}=\frac{-12}{-4}
=+3
$