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4-1.Complex numbers
medium
If $z =2+3 i$, then $z ^{5}+(\overline{ z })^{5}$ is equal to.
A
$244$
B
$224$
C
$245$
D
$265$
(JEE MAIN-2022)
Solution
$z^{5}+(\bar{z})^{5}=(2+3 i)^{5}+(2-3 i)^{5}$
$=2\left({ }^{5} C_{0} 2^{5}+{ }^{5} C_{2} 2^{3}(3 i)^{2}+{ }^{5} C_{4} 2^{1}(3 i)^{4}\right)$
$=2(32+10 \times 8(-9)+5 \times 2 \times 81)=244$
Standard 11
Mathematics