V=4i*(12-7i)

Solution for V=4i*(12-7i) equation:

=4V(12-7V)

We move all terms to the left:

-(4V(12-7V))=0

We add all the numbers together, and all the variables

-(4V(-7V+12))=0


We calculate terms in parentheses: -(4V(-7V+12)), so:

4V(-7V+12)

We multiply parentheses

-28V^2+48V

Back to the equation:

-(-28V^2+48V)


We get rid of parentheses

28V^2-48V=0

a = 28; b = -48; c = 0;
Δ = b2-4ac
Δ = -482-4·28·0
Δ = 2304
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2304}=48$
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-48)-48}{2*28}=\frac{0}{56}
=0
$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-48)+48}{2*28}=\frac{96}{56}
=1+5/7
$