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Binomial Expansion — IB Maths AA HL Practice

Binomial expansion is one of the most reliable mark-earners on IB Maths AA HL Paper 1. This free practice ladder climbs from evaluating $\binom{n}{r}$ to the hardest exam types — the term independent of $x$ and products of brackets — re-teaching the step whenever you slip.

The idea

$\dbinom{n}{r}$ ("n choose r") counts how many ways to choose $r$ things from $n$ when order doesn't matter: $\dfrac{n!}{r!(n-r)!}$.
💡 Since $\dbinom{n}{r}=\dbinom{n}{n-r}$, $\dbinom74=\dbinom73$ — compute the one with the smaller bottom number.

What you'll master

Sample questions

Every attempt generates new numbers — the practice below never runs out.

Practise it now

Frequently asked questions

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