(4v-13)(5v+7)=0

Solution for (4v-13)(5v+7)=0 equation:

(4v-13)(5v+7)=0

We multiply parentheses ..

(+20v^2+28v-65v-91)=0

We get rid of parentheses

20v^2+28v-65v-91=0

We add all the numbers together, and all the variables

20v^2-37v-91=0

a = 20; b = -37; c = -91;
Δ = b2-4ac
Δ = -372-4·20·(-91)
Δ = 8649
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{8649}=93$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-37)-93}{2*20}=\frac{-56}{40}
=-1+2/5
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-37)+93}{2*20}=\frac{130}{40}
=3+1/4
$