Number and algebraCourse skill

Generalised binomial expansion

Expand a negative or fractional power near zero and state an interval of validity.

  • Use .
  • For the powers used here, require . Solve this restriction for .
  • The cubic truncation contains the terms through ; it is not the full function.

Example 1

Expand up to and including the term in , and state an interval of validity.

Identify the power and the inside term.Use the cubic truncation.Coefficient of .Coefficient of .Coefficient of .

Example 2

Expand up to and including the term in , and state an interval of validity.

Identify the power and the inside term.Use the cubic truncation.Coefficient of .Coefficient of .Coefficient of .

Remember
For , the open interval is sufficient. Endpoints are not included in this card.

Your turn

5 practice questions
Question 1

Expand up to and including the term in , and state an interval of validity.

Check answer
Identify the power and the inside term.Use the cubic truncation.Coefficient of .Coefficient of .Coefficient of .

The displayed polynomial is the expansion truncated after . Higher-order terms are omitted.

Question 2

Expand up to and including the term in , and state an interval of validity.

Check answer
Identify the power and the inside term.Use the cubic truncation.Coefficient of .Coefficient of .Coefficient of .

The displayed polynomial is the expansion truncated after . Higher-order terms are omitted.

Question 3

Expand up to and including the term in , and state an interval of validity.

Check answer
Identify the power and the inside term.Use the cubic truncation.Coefficient of .Coefficient of .Coefficient of .

The displayed polynomial is the expansion truncated after . Higher-order terms are omitted.

Question 4

Expand up to and including the term in , and state an interval of validity.

Check answer
Identify the power and the inside term.Use the cubic truncation.Coefficient of .Coefficient of .Coefficient of .

The displayed polynomial is the expansion truncated after . Higher-order terms are omitted.

Question 5

Expand up to and including the term in , and state an interval of validity.

Check answer
Identify the power and the inside term.Use the cubic truncation.Coefficient of .Coefficient of .Coefficient of .

The displayed polynomial is the expansion truncated after . Higher-order terms are omitted.