I keep getting “Chain rule” questions wrong in Differentiation. What's the trap?
forgetting to multiply by the inner derivative.
The usual trap: forgetting to multiply by the inner derivative. How to avoid it: for sin(2x), it's cos(2x)×2 — don't drop the ×2. Go back to the definition — to differentiate a composite function, differentiate the outer function and multiply by the derivative of the inner.
Key point
Chain rule
Common mistake
forgetting to multiply by the inner derivative.
Memory tip
for sin(2x), it's cos(2x)×2 — don't drop the ×2.
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