I keep getting “General term” questions wrong in Binomial Theorem. What's the trap?
treating the general term as the rth term instead of the (r+1)th.
The usual trap: treating the general term as the rth term instead of the (r+1)th. How to avoid it: to find a specific term, set the exponent and solve for r, then plug in. Go back to the definition — the (r+1)th term is T_(r+1) = nCr·a^(n−r)·b^r.
Key point
General term
Common mistake
treating the general term as the rth term instead of the (r+1)th.
Memory tip
to find a specific term, set the exponent and solve for r, then plug in.
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