9i(7i+9)+6(-3+7i)
The answer I get is 63i^2+123i-18
but I think the answer is supposed to be -81 + 123 i
I don't understand why.
Since you are dealing with complex numbers, i2 = -1, so replace i2 with -1.
63i2 + 123i - 18 = 63(-1) + 123i - 18 = -63 + 123i - 18 = -81 + 123i.
