Products and quotients of powers
Use these rules for matching bases. All variables appearing in a denominator must be nonzero. This section introduces zero results from complete cancellation; negative result indices follow later
- Add indices for the same base A product joins the factors from both powers. Keep the base unchanged \(\displaystyle a^3\times a^4=a^{3+4}=a^7\)
- Subtract when dividing Cancel matching factors. The denominator must be nonzero \(\displaystyle \frac{a^8}{a^3}=a^{8-3}=a^5\quad(a\ne0)\)
- Keep different bases separate Collect powers of each letter independently \(\displaystyle a^2b^5\times a^3b^2=a^5b^7\)
- Calculate coefficients separately Multiply or divide numerical factors using ordinary arithmetic; a quotient coefficient can be a fraction \(\displaystyle 3x^2\times4x^3=12x^5\)
- Complete cancellation gives one For a nonzero base, equal numerator and denominator powers cancel to 1. A resulting index 0 does not mean the whole expression is 0. \(\displaystyle \frac{a^3}{a^3}=a^0=1\quad(a\ne0)\)
Worked example
Simplify the expression. Assume a and b are nonzero
- \(\displaystyle 12\div3=4\)Divide the numerical coefficients
- \(\displaystyle a^{7}\div a^{2}=a^{7-2}=a^{5}\)Subtract the denominator index from the numerator index for a.
- \(\displaystyle b^{5}\div b^{3}=b^{5-3}=b^{2}\)Apply the same quotient rule separately to b.
- \(\displaystyle \frac{12a^{7}b^{5}}{3a^{2}b^{3}}=4a^{5}b^{2}\)Combine the coefficient and the simplified powers
Common mistakes
Difficulty levels
Questions about this topic
Why do multiplied powers add indices?+
For positive integer indices, multiplication joins all the factors. Three copies followed by four copies make seven copies of the same base
What restriction applies to divided powers?+
Every denominator must be nonzero. Cancelling factors does not remove this restriction from the original expression
What if an index becomes zero?+
A nonzero base to index zero is 1. Omit that factor from the final product, but enter 0 when a question asks for its index
Why are coefficients handled separately?+
Coefficients are ordinary numerical factors. Their product or quotient is calculated separately from the indices of matching letters
Can I use a calculator?+
No. This topic is practised without a calculator
Which year level and chapter is this?+
Year 9 Mathematics, chapter 6: Indices and surds