New
New
Year 10
Higher

The laws of indices - negative and zero exponents

I can use the laws of indices with negative and zero exponents.

New
New
Year 10
Higher

The laws of indices - negative and zero exponents

I can use the laws of indices with negative and zero exponents.

Lesson details

Key learning points

  1. A calculator can be helpful to explore what happens when the exponent is zero or negative.
  2. Any term with an exponent of zero is equal to one.
  3. A negative exponent tells you how many times you need to multiply the reciprocal of the base.
  4. Negative exponents appear when writing very small numbers in standard form.

Common misconception

Any number with an index of 0 equates to 0

Reiterate the division of any number by itself is 1. This applies with laws of indices too. E.g 8^4 / 8^4 = 8^0. Any number divided by itself gives 1, therefore 8^0 = 1. For more advanced understanding, algebraic can be used instead of numbers.

Keywords

  • Reciprocal - A reciprocal is the multiplicative inverse of any non-zero number. Any non-zero number multiplied by its reciprocal is equal to 1

  • Indices - An exponent is a number positioned above and to the right of a base value. It indicates repeated multiplication. An alternative word for this is index (plural indices).

Pupils create 5 of their own questions which give an answer of 5 using a range of operations and a term with an index of 0. For example, 9^0 x 5 = 5, 5x^0 = 5, 10x^0/2 = 5, etc
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
What is the value of $$x$$ for $$(m^x)^8 = m^{24}$$
Correct Answer: 3
Q2.
What is the value of $$x$$ for $$(m^5)^5 = m^x$$
Correct Answer: 25
Q3.
What is the value of $$x$$ for $$(m^3)^x = m^9$$
Correct Answer: 3
Q4.
What is the value of $$x$$ for $$(m^8)^3 = m^x$$
Correct Answer: 24
Q5.
What is the value of $$x$$ for $$\frac{1}{4} = \frac{1}{2^x}$$
Correct Answer: 2
Q6.
What is the value of $$x$$ for $$\frac{1}{64} = \frac{1}{2^x}$$
Correct Answer: 6

6 Questions

Q1.
What is the value of $$x$$ for $$(m^x)^{-8} = m^{24}$$
Correct Answer: -3
Q2.
What is the value of $$x$$ for $$(m^{-5})^5 = m^x$$
Correct Answer: -25
Q3.
What is the value of $$x$$ for $$(m^3)^x = m^{-3}$$
Correct Answer: -1
Q4.
What is the value of $$x$$ for $$\frac{1}{4} = 2^x$$
Correct Answer: -2
Q5.
What is the value of $$x$$ for $$\frac{1}{64} = 2^x$$
Correct Answer: -6
Q6.
What is the value of $$a$$ for $$5^8 \times 5^a = 5^6$$?
Correct Answer: -2