(7c-5)(2-9c)=0

Solution for (7c-5)(2-9c)=0 equation:

(7c-5)(2-9c)=0

We add all the numbers together, and all the variables

(7c-5)(-9c+2)=0

We multiply parentheses ..

(-63c^2+14c+45c-10)=0

We get rid of parentheses

-63c^2+14c+45c-10=0

We add all the numbers together, and all the variables

-63c^2+59c-10=0

a = -63; b = 59; c = -10;
Δ = b2-4ac
Δ = 592-4·(-63)·(-10)
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(59)-31}{2*-63}=\frac{-90}{-126}
=5/7
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(59)+31}{2*-63}=\frac{-28}{-126}
=2/9
$