Area under a curve
The Goal
Find the exact area under the curve y = 8 - x2 and above the x-axis.
The Mistake
Find the mistake:
(Roll the mouse over the math to see a hint in red)
The Correction
(Roll the mouse over the area above to see the correction in blue)
An Explanation
The mistake was to approximate √8 by 2.82. The instructions were to find the exact value of the area, so the problem should be worked out with the exact values. This problem is one for which your calculator should be left turned off.