(-7i)(9i)=i

Solution for (-7i)(9i)=i equation:

(-7i)(9i)=i

We move all terms to the left:

(-7i)(9i)-(i)=0

We add all the numbers together, and all the variables

-1i+(-7i)9i=0

We multiply parentheses

-63i^2-1i=0

a = -63; b = -1; c = 0;
Δ = b2-4ac
Δ = -12-4·(-63)·0
Δ = 1
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1}=1$
$i_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-1}{2*-63}=\frac{0}{-126}
=0
$
$i_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+1}{2*-63}=\frac{2}{-126}
=-1/63
$