4x^2+28x^2+21x-18=0

Solution for 4x^2+28x^2+21x-18=0 equation:

4x^2+28x^2+21x-18=0

We add all the numbers together, and all the variables

32x^2+21x-18=0

a = 32; b = 21; c = -18;
Δ = b2-4ac
Δ = 212-4·32·(-18)
Δ = 2745
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:

$\sqrt{\Delta}=\sqrt{2745}=\sqrt{9*305}=\sqrt{9}*\sqrt{305}=3\sqrt{305}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-3\sqrt{305}}{2*32}=\frac{-21-3\sqrt{305}}{64}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+3\sqrt{305}}{2*32}=\frac{-21+3\sqrt{305}}{64}
$