(5x*3x)-(x*x)=126

Solution for (5x*3x)-(x*x)=126 equation:

(5x*3x)-(x*x)=126

We move all terms to the left:

(5x*3x)-(x*x)-(126)=0

We add all the numbers together, and all the variables

(+5x*3x)-(+x*x)-126=0

We get rid of parentheses

5x*3x-x*x-126=0

Wy multiply elements

15x^2-1x^2-126=0

We add all the numbers together, and all the variables

14x^2-126=0

a = 14; b = 0; c = -126;
Δ = b2-4ac
Δ = 02-4·14·(-126)
Δ = 7056
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7056}=84$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-84}{2*14}=\frac{-84}{28}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+84}{2*14}=\frac{84}{28}
=3
$