(7s+5)(2s-3)=0

Solution for (7s+5)(2s-3)=0 equation:

(7s+5)(2s-3)=0

We multiply parentheses ..

(+14s^2-21s+10s-15)=0

We get rid of parentheses

14s^2-21s+10s-15=0

We add all the numbers together, and all the variables

14s^2-11s-15=0

a = 14; b = -11; c = -15;
Δ = b2-4ac
Δ = -112-4·14·(-15)
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$s_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-11)-31}{2*14}=\frac{-20}{28}
=-5/7
$
$s_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-11)+31}{2*14}=\frac{42}{28}
=1+1/2
$