Choosing the substitution
Integration · Lecture 4
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Choosing the substitution
Integration · Lecture 4
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Each topic begins with a concise lecture and worked examples. Pause, replay, and pick up where you left off.
Integration — Lecture notes
PDF · 12 pages
Remark · page 3
Check whether part of the integrand is the derivative of another part. If it is, a substitution may simplify the integral.
∫ (2x + 1) / √(x² + x + 1) dx
Hint: the numerator is the derivative of the radicand.
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Practice questions
Paper 1 · Integration
Which substitution is most efficient for
∫ (2x + 1) / √(x² + x + 1) dx
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Worked solution
Shown step by step
Step 1 · Recognise structure
Numerator is d/dx of the radicand.
Step 2 · Substitute
Let u = x² + x + 1, so du = (2x + 1) dx.
Step 3 · Integrate
∫ u^(-1/2) du = 2√u + C
Final answer
2√(x² + x + 1) + C
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This sample is from the Paper 1 integration module.
A lesson from the Paper 1 integration module.
Integration by substitution
Paper 1 · Sample lecture
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