-4x^2-16X+4=18

Solution for -4x^2-16X+4=18 equation:

-4x^2-16x+4=18

We move all terms to the left:

-4x^2-16x+4-(18)=0

We add all the numbers together, and all the variables

-4x^2-16x-14=0

a = -4; b = -16; c = -14;
Δ = b2-4ac
Δ = -162-4·(-4)·(-14)
Δ = 32
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{32}=\sqrt{16*2}=\sqrt{16}*\sqrt{2}=4\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-16)-4\sqrt{2}}{2*-4}=\frac{16-4\sqrt{2}}{-8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-16)+4\sqrt{2}}{2*-4}=\frac{16+4\sqrt{2}}{-8}
$