-5i(10-15i)=0

Solution for -5i(10-15i)=0 equation:

-5i(10-15i)=0

We add all the numbers together, and all the variables

-5i(-15i+10)=0

We multiply parentheses

75i^2-50i=0

a = 75; b = -50; c = 0;
Δ = b2-4ac
Δ = -502-4·75·0
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-50)-50}{2*75}=\frac{0}{150}
=0
$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-50)+50}{2*75}=\frac{100}{150}
=2/3
$