SAT Math Multiple Choice Question 945: Answer and Explanation
13. What is the value of?
- A. -i
- B. i
- C. -1
- D. 1
Correct Answer: C
Category: Additional Topics in Math / Imaginary Numbers
Strategic Advice: Powers of i cycle in the pattern i, -1, -i, 1. Memorizing this pattern may save you valuable time on Test Day. To determine the value of a high power of i, divide the exponent by 4 (the number of terms in the cycle). The remainder tells you which term in the pattern is the answer. For example, i11 = i3 because.
Getting to the Answer: When 48 is divided by 4, the remainder is 0; therefore, i48 = i4, which is 1. Don't forget about the negative sign in front of it, though. This makes the correct answer -1, which is (C).