Answer:
d)
Step-by-step explanation:
we know, that i = sqrt(-1)
so, i² = -1
i³ = -i
i⁴ = -i × i = - -1 = 1
i⁵ = i⁴×I = 1×i = i
and the cycle begins again for any higher exponents.
so, we find out what i^n is, by dividing n by 4 and look at the remainder.
remainder = 0, i^n = 1
remainder = 1, i^n = i
remainder = 2, i^n = -1
remainder = 3, i^n = -i
so, what is 139 in this regard ?
139 ÷ 4 = 34
remainder 3
so, i¹³⁹ = -i
a) 322 ÷ 4 = 80
remainder 2. not equivalent.
b) 304 ÷ 4 = 76
remainder 0. not equivalent.
c) 221 ÷ 4 = 55
remainder 1. not equivalent.
d) 239 ÷ 4 = 59
remainder 3. this IS equivalent.
