Problem preview
N-CN.1 Warmup M2-055-A01-V01

Understand i as a number with i^2=-1 and represent complex numbers as a+bi.

Simplify powers of $i$ using the repeating cycle $i, -1, -i, 1$

Problem

Evaluate \(i^{5}\) by writing \(5=4+1\) and using \(i^{4}=1\). State the resulting value from the \(\text{four}\text{-}\text{power}~\text{cycle}\).

Big Picture

What this problem is really about

Powers of the imaginary unit repeat in a four-step cycle, so the exponent’s remainder locates the value. We’ll build the first four powers, separate complete groups of four from the exponent, reduce the leftover factor, and check that the modulo-four position matches the cycle.

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Four variants of this problem type
Curriculum context
Course
Math II
Standard
N-CN.1
Category
Number and Quantity
Domain
The Complex Number System
Objective
Understand i as a number with i^2=-1 and represent complex numbers as a+bi.
Problem type
Simplify powers of $i$ using the repeating cycle $i, -1, -i, 1$