(5c-3)(c+5)=A

Solution for (5c-3)(c+5)=A equation:

(5c-3)(c+5)=

We move all terms to the left:

(5c-3)(c+5)-()=0

We add all the numbers together, and all the variables

(5c-3)(c+5)=0

We multiply parentheses ..

(+5c^2+25c-3c-15)=0

We get rid of parentheses

5c^2+25c-3c-15=0

We add all the numbers together, and all the variables

5c^2+22c-15=0

a = 5; b = 22; c = -15;
Δ = b2-4ac
Δ = 222-4·5·(-15)
Δ = 784
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{784}=28$
$c_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(22)-28}{2*5}=\frac{-50}{10}
=-5
$
$c_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(22)+28}{2*5}=\frac{6}{10}
=3/5
$