(7i-2)(3i+1)=0

Solution for (7i-2)(3i+1)=0 equation:

(7i-2)(3i+1)=0

We multiply parentheses ..

(+21i^2+7i-6i-2)=0

We get rid of parentheses

21i^2+7i-6i-2=0

We add all the numbers together, and all the variables

21i^2+i-2=0

a = 21; b = 1; c = -2;
Δ = b2-4ac
Δ = 12-4·21·(-2)
Δ = 169
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{169}=13$
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-13}{2*21}=\frac{-14}{42}
=-1/3
$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+13}{2*21}=\frac{12}{42}
=2/7
$