Mathematics

Mathematics

Problem

For g(x)=x+1csc⁡xg(x)=\dfrac{x+1}{\csc x}, evaluate g′(x)g'(x). a) sin⁡x[1−(x+1)cot⁡x]\sin x\left[1-(x+1)\cot x\right] b) csc⁡x[1+(x+1)cot⁡x]\csc x\left[1+(x+1)\cot x\right] c) sin⁡x[1+(x+1)cot⁡x]\sin x\left[1+(x+1)\cot x\right] d) sin⁡x[(x+1)cot⁡x]\sin x\left[(x+1)\cot x\right]
Intuitive explanation

The key is recognizing that csc⁡x=1sin⁡x\csc x = \frac{1}{\sin x}, so you can rewrite g(x)=(x+1)sin⁡xg(x) = (x+1)\sin x — transforming a quotient into a product. Once you see it as a product, the product rule becomes your natural tool, and you'll need the derivatives of both (x+1)(x+1) and sin⁡x\sin x. This small rewrite often makes a messy-looking problem much cleaner.

Intuitive explanation

The key is recognizing that csc⁡x=1sin⁡x\csc x = \frac{1}{\sin x}, so you can rewrite g(x)=(x+1)sin⁡xg(x) = (x+1)\sin x — transforming a quotient into a product. Once you see it as a product, the product rule becomes your natural tool, and you'll need the derivatives of both (x+1)(x+1) and sin⁡x\sin x. This small rewrite often makes a messy-looking problem much cleaner.

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