168=78+45x2

Solution for 168=78+45x2 equation:

168=78+45x^2

We move all terms to the left:

168-(78+45x^2)=0

We get rid of parentheses

-45x^2-78+168=0

We add all the numbers together, and all the variables

-45x^2+90=0

a = -45; b = 0; c = +90;
Δ = b2-4ac
Δ = 02-4·(-45)·90
Δ = 16200
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:

$\sqrt{\Delta}=\sqrt{16200}=\sqrt{8100*2}=\sqrt{8100}*\sqrt{2}=90\sqrt{2}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-90\sqrt{2}}{2*-45}=\frac{0-90\sqrt{2}}{-90}
=-\frac{90\sqrt{2}}{-90}
=-\frac{\sqrt{2}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+90\sqrt{2}}{2*-45}=\frac{0+90\sqrt{2}}{-90}
=\frac{90\sqrt{2}}{-90}
=\frac{\sqrt{2}}{-1}
$