2x^2-28x=3x^2-7x-4

Solution for 2x^2-28x=3x^2-7x-4 equation:

2x^2-28x=3x^2-7x-4

We move all terms to the left:

2x^2-28x-(3x^2-7x-4)=0

We get rid of parentheses

2x^2-3x^2-28x+7x+4=0

We add all the numbers together, and all the variables

-1x^2-21x+4=0

a = -1; b = -21; c = +4;
Δ = b2-4ac
Δ = -212-4·(-1)·4
Δ = 457
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-\sqrt{457}}{2*-1}=\frac{21-\sqrt{457}}{-2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+\sqrt{457}}{2*-1}=\frac{21+\sqrt{457}}{-2}
$