18x^2+256x+21=0

Solution for 18x^2+256x+21=0 equation:

18x^2+256x+21=0

a = 18; b = 256; c = +21;
Δ = b2-4ac
Δ = 2562-4·18·21
Δ = 64024
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:

$\sqrt{\Delta}=\sqrt{64024}=\sqrt{4*16006}=\sqrt{4}*\sqrt{16006}=2\sqrt{16006}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(256)-2\sqrt{16006}}{2*18}=\frac{-256-2\sqrt{16006}}{36}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(256)+2\sqrt{16006}}{2*18}=\frac{-256+2\sqrt{16006}}{36}
$