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Throughout this website, you will find lots of free resources to help you do the best for your A-Level in Maths. We have detailed explanations and examples for all topic areas (currently AS),  A-Level practice papers for the new maths specification, past exam papers, questions grouped by topic and many more resources.


Question of the Week

The diagram shows the curve y=x^2 and the straight line y=0.5x+2. Find the shaded area shown in purple to 3 decimal places.

definite integrals
Solution:

The area shown in purple can be found by subtracting the area beneath the quadratic from the trapezium beneath the straight line. To find the area beneath the quadratic we use definite integrals but we must first identify the limits. Clearly, the lower limit is 0. The upper limit, however, needs to be found by solving x^2=0.5x+2, that is, finding the x-coordinate of the intersection of the two graphs:

x^2-0.5x-2=0\hspace{15pt}\Longrightarrow\hspace{15pt}x=-1.186..., 1.686....

See solving quadratics. Taking the positive x-coordinate, we have the area beneath the quadratic as the following definite integral:

\int_0^{1.686} x^2\,dx=\left[\frac{1}{3}x^3\right]_0^{1.686}=1.598...

to 3 decimal places. The area of the trapezium (half the sum of the parallel sides multiplied by the distance between them) is given by

0.5\times(2+0.5\times 1.686+2)\times1.686=4.083...

to 3 decimal places. Hence, the area of the region shaded in green is 4.083-1.598=2.485 square units to 3 decimal places.

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Past A-Level Maths papers for all maths modules examined by Edexcel dating back to 2005.

pastpaper


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