Worked solution
Practise power, chain and product rules together
Differentiate (a) and (b) with respect to .
CJC · Lecture · Self-Practice 1
(a) Convert the radicals to powers
For , the expression is . Differentiate to get , matching the printed answer. The square-root denominator restricts the combined real domain to .
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(b) Apply the product and chain rules
The derivative is .
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(b) Factor without cancelling possible zeros
Take out . The remaining bracket is . Thus the result is , exactly the printed answer. This polynomial derivative is valid for all real ; factoring does not exclude zeros of the factors.
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Common mistakes
The square and cube roots in part (a) are different; both chain factors are needed in part (b).
Solution notes
Both originals print the final answers but not intermediate working. The intermediate derivation and domain commentary here are independently authored and checked against both printed answers.