(4+v)(5v-8)=0

Solution for (4+v)(5v-8)=0 equation:

(4+v)(5v-8)=0

We add all the numbers together, and all the variables

(v+4)(5v-8)=0

We multiply parentheses ..

(+5v^2-8v+20v-32)=0

We get rid of parentheses

5v^2-8v+20v-32=0

We add all the numbers together, and all the variables

5v^2+12v-32=0

a = 5; b = 12; c = -32;
Δ = b2-4ac
Δ = 122-4·5·(-32)
Δ = 784
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{784}=28$
$v_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(12)-28}{2*5}=\frac{-40}{10}
=-4
$
$v_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(12)+28}{2*5}=\frac{16}{10}
=1+3/5
$