(7-5i)(2-8i)=0

Solution for (7-5i)(2-8i)=0 equation:

(7-5i)(2-8i)=0

We add all the numbers together, and all the variables

(-5i+7)(-8i+2)=0

We multiply parentheses ..

(+40i^2-10i-56i+14)=0

We get rid of parentheses

40i^2-10i-56i+14=0

We add all the numbers together, and all the variables

40i^2-66i+14=0

a = 40; b = -66; c = +14;
Δ = b2-4ac
Δ = -662-4·40·14
Δ = 2116
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2116}=46$
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-66)-46}{2*40}=\frac{20}{80}
=1/4
$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-66)+46}{2*40}=\frac{112}{80}
=1+2/5
$