The value of - 1 + i 3 1 - i 30 is :

The value of-1+i31-i30 is :
  1. 65
  2. 215 i
  3. -215
  4. -215i

Solution

-1+3i1-i30=2cos2π3+isin2π32cosπ4-isinπ430

=230(cos20π+isin20π)215cos15π2-isin15π2

=215(1+0i)(0+i)=-215i

Asked in: JEE Main 2020 (05 Sep Shift 2)

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