4c2-9c=9

Solution for 4c2-9c=9 equation:

4c^2-9c=9

We move all terms to the left:

4c^2-9c-(9)=0

a = 4; b = -9; c = -9;
Δ = b2-4ac
Δ = -92-4·4·(-9)
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-15}{2*4}=\frac{-6}{8}
=-3/4
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+15}{2*4}=\frac{24}{8}
=3
$