GCSE Maths (Edexcel)

435 videos | 33 hours

Negative Fractional Indices

Please subscribe to watch this video.

This, and all other videos, are included in our premium subscriptions.

Premium accounts get access to all videos.

Number Structure and Calculation

Negative Fractional Indices

5:34 Advanced Indicies & Roots
Spec N7
Previous Fractional Indices Next Estimating Roots
  • Negative fractional indices require applying the rules for both negative and fractional indices.
  • For negative indices, a to the power of minus x, take the reciprocal: 1 divided by a to the x.
  • For fractional indices, a to the power of x over y, take the yth root of a to the power of x or take the yth root of a and then raise to the power of x.
  • Manipulating negative fractional indices is important in mathematical sciences.
  • Example: Evaluate 64 to the minus two thirds. Rewrite as 1 over 64 to the 2 thirds. Take the cube root of 64 and square the answer to get 1 over 4 squared, which is 1/16.
  • Example: Evaluate 27/8 to the power of minus four thirds. Rewrite as the reciprocal of 27/8 to the four thirds, which is 8/27 to the power of four thirds. Take the cube root of 8 and 27, then raise to the power of four to get 16/81.

Please subscribe to access these revision notes.

This, and all other video notes, are included in our premium subscriptions.

Premium accounts get access to all videos and revision notes.