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There are 3 complex numbers a + bi, c + di, and e + fi. If b = 7, e = -a - c, and the sum of the numbers is -3i, find  d + f.

 Feb 23, 2021
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$(a+c+e)+(b+d+f)i=-3i\implies (a+c-a-c)+(7+d+f)i=-3i\implies (d+f+7)i=-3i\implies d+f+7=-3\impies d+f=-\boxed{-10}$.

 Feb 23, 2021

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