18c-2c*c=4

Solution for 18c-2c*c=4 equation:

18c-2c*c=4

We move all terms to the left:

18c-2c*c-(4)=0

Wy multiply elements

-2c^2+18c-4=0

a = -2; b = 18; c = -4;
Δ = b2-4ac
Δ = 182-4·(-2)·(-4)
Δ = 292
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{292}=\sqrt{4*73}=\sqrt{4}*\sqrt{73}=2\sqrt{73}$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-2\sqrt{73}}{2*-2}=\frac{-18-2\sqrt{73}}{-4}
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+2\sqrt{73}}{2*-2}=\frac{-18+2\sqrt{73}}{-4}
$