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Worked solution

Rewrite radicals as powers

Integrate with respect to xx: (a) 3x2+6x2\frac3{x^2}+6x^2; (b) x3−x2+4x−7x\frac{x^3-x^2+4x-7}{\sqrt{x}}.

CJC · Lecture · Self-Practice 1

(a)

∫(3x−2+6x2) dx=−3x−1+2x3+C=−3x+2x3+C\int(3x^{-2}+6x^2)\,dx=-3x^{-1}+2x^3+C=-\frac3x+2x^3+C, for x≠0x\ne0.

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(b)

For x>0x>0, divide each term by x1/2x^{1/2}: ∫(x5/2−x3/2+4x1/2−7x−1/2) dx=27x7/2−25x5/2+83x3/2−14x1/2+C\int(x^{5/2}-x^{3/2}+4x^{1/2}-7x^{-1/2})\,dx=\frac27x^{7/2}-\frac25x^{5/2}+\frac83x^{3/2}-14x^{1/2}+C. This reproduces the printed answer.

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Common mistakes

The denominator in (b) is the square root of x; retain all four numerator terms and their signs.

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