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Chapter exploration

Definite integrals, areas and volumes

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For y=x2y=x^2 on [0,2][0,2], predict whether left- and right-endpoint rectangle sums lie above or below the integral.

In a spreadsheet or calculator, use n equal strips with width 2/n2/n and compare n=2,4,8n=2,4,8. Keep a column for height times width, then sum it.

Compare both sequences with the exact integral and explain why their separation shrinks.

State which property of this curve justifies the ordering; endpoint choice alone does not give that ordering for every curve.

Related interactive example

Explore this related example, then return to the prediction task above.

Add each feature an examiner looks for

Start with the bare curve and line. Switch on each feature to see where it goes and how you would find it.

Switch on a feature to add it to the sketch and see how it is found. A full-mark sketch shows all of them.

  • Bell curve y = 2/[1+(x−2)²]
  • Horizontal line y = 1
  • Line of symmetry x = 2
Ideas to try
  1. Switch on “Meets y = 1” first. Could you predict both x-values from the symmetry alone?
  2. Hover or tap along the curve to read off coordinates.
Open the full interactive problem →
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