(-3i)(5i)=15i

Solution for (-3i)(5i)=15i equation:

(-3i)(5i)=15i

We move all terms to the left:

(-3i)(5i)-(15i)=0

We add all the numbers together, and all the variables

-15i+(-3i)5i=0

We multiply parentheses

-15i^2-15i=0

a = -15; b = -15; c = 0;
Δ = b2-4ac
Δ = -152-4·(-15)·0
Δ = 225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{225}=15$
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-15)-15}{2*-15}=\frac{0}{-30}
=0
$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-15)+15}{2*-15}=\frac{30}{-30}
=-1
$