Brainlag PlusWhat negative and fractional indices mean, evaluating powers like 8^(−2/3) exactly, and solving equations with the unknown in the index.
Negative indices mean "one over"
Carry on the pattern 2³ = 8, 2² = 4, 2¹ = 2, 2⁰ = 1: each step divides by 2, so 2⁻¹ = 1/2 and 2⁻³ = 1/8.
a⁻ⁿ = 1/aⁿ
A negative index never makes the answer negative: 5⁻² = 1/25. For a fraction, flip it: (2/3)⁻¹ = 3/2.
The rest of this lesson and its 7 practice questions are in Plus.
Screen 1 of 4, free to read.
- 7 exam-style questions, marked as you go, each with a worked solution
- The Scientific Calculator beside every question
- Anything you get wrong is saved to your flashcards