Find (2+3i)-(-5+8i)

also

Find (5-9i)(2+3i)

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- Mar 9th 2010, 07:38 AMMhockey02Write your answer in a + bi form
Find (2+3i)-(-5+8i)

also

Find (5-9i)(2+3i) - Mar 9th 2010, 08:11 AMe^(i*pi)
When adding or subtracting complex numbers add/subtract the real component and the imaginary component separately

$\displaystyle (a+bi)-(c+di) = (a-c) + (b-d)i$

When multiplying treat it the same as you would with any polynomial. Just recall that $\displaystyle i^2 = -1$ - Mar 9th 2010, 08:31 AMMhockey02
So the answer for the first one is -4 and the second one is 9?

- Mar 9th 2010, 08:56 AMe^(i*pi)