Question 221551
a) i^15
i^15 = i^3 = -1*i
= -i
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b) (2-i) / (5+i)
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Multiply NUM and DEN by the conjugate of the DEN
= (2-i)*(5-i)/(5+i)*(5-i)
= (10 - 1 - 7i)/(25+1)
= (9-7i)/26