7i(3+4i)=0

Solution for 7i(3+4i)=0 equation:

7i(3+4i)=0

We add all the numbers together, and all the variables

7i(4i+3)=0

We multiply parentheses

28i^2+21i=0

a = 28; b = 21; c = 0;
Δ = b2-4ac
Δ = 212-4·28·0
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(21)-21}{2*28}=\frac{-42}{56}
=-3/4
$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(21)+21}{2*28}=\frac{0}{56}
=0
$