1 + 4i / 1 - i Thanks in advance!
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Originally Posted by Hapa 1 + 4i / 1 - i Thanks in advance! Is it (1 + 4i)/(1 - i), that is, $\displaystyle \frac{1 + 4i}{1 - i} ?$ Please be less ambiguous when you post.
My apologies. Yes, it is as you listed (1 + 4i) / (1 - i)
Originally Posted by Hapa My apologies. Yes, it is as you listed (1 + 4i) / (1 - i) Use the difference of two squares $\displaystyle a^2-b^2 = (a-b)(a+b)$ and $\displaystyle i^2 = -1$ to rationalise the denominator Spoiler: $\displaystyle \frac{1+4i}{1-i} \times \frac{1+i}{1+i} = \frac{(1+4i)(1+i)}{(1-i)(1+i)}$ $\displaystyle \frac{1+i+4i+4i^2}{1-(i^2)} = \frac{-3+5i}{2} = -1.5+2.5i$ google can actually do your sum XD: Click me
Last edited by e^(i*pi); Apr 12th 2009 at 05:30 PM. Reason: adding google link
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