9c=7c^2

Solution for 9c=7c^2 equation:

9c=7c^2

We move all terms to the left:

9c-(7c^2)=0

determiningTheFunctionDomain
-7c^2+9c=0

a = -7; b = 9; c = 0;
Δ = b2-4ac
Δ = 92-4·(-7)·0
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-9}{2*-7}=\frac{-18}{-14}
=1+2/7
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+9}{2*-7}=\frac{0}{-14}
=0
$