Multiplying (-3-7i) by (-1 + i)
In general, to multiply two complex numbers, this is the formula:
(x + yi)(u + vi) = (xu - yv) + (xv + yu)i
Using the formula with the numbers from the question:
x = -3
y = -7
u = -1
v = 1
(-3 - 7i)(-1 + i) =
[(-3)((-1) - (-7)(1)] + [(-3)(1) + (-7)(-1)]i =
[3 + 7] + [-3 + 7]i =
10 + 4i
Answer:
10 + 4i