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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(+49i^2-14i+56i-16)=0

We get rid of parentheses

49i^2-14i+56i-16=0

We add all the numbers together, and all the variables

49i^2+42i-16=0

a = 49; b = 42; c = -16;
Δ = b2-4ac
Δ = 422-4·49·(-16)
Δ = 4900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4900}=70$
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(42)-70}{2*49}=\frac{-112}{98}
=-1+1/7
$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(42)+70}{2*49}=\frac{28}{98}
=2/7
$