Q. Which of the following is equivalent to the complex number i21 ?Choose 1 answer:(A) 1(B) i(C) −1(D) −i
Determine pattern of powers: Determine the pattern of powers of i.The powers of i follow a cyclical pattern:i1=ii2=−1i3=−ii4=1Then the pattern repeats every 4 powers.
Reduce exponent modulo 4: Reduce the exponent 21 modulo 4 to find its equivalent in the pattern.21mod4=1This means that i21 is equivalent to i1 in the pattern.
Match reduced exponent to pattern: Match the reduced exponent to the pattern.Since 21mod4=1, we look at the pattern and see that i1=i.