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8.1 Assessed Exercises 1

Solutions in tutor’s pigeonhole by 17:00 on Tuesday 22nd November, please. Feedback is available from the moodle website.

A1.1. i) Factorize the polynomial g(x)=x4+2x3+4x2+8xg(x)=x^{4}+2x^{3}+4x^{2}+8x as a product of linear factors and irreducible quadratic polynomials.

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ii) Evaluate the definite integral

23/323x3+5x2-6x+8x4+2x3+4x2+8xdx.\int_{2\sqrt{3}/3}^{2\sqrt{3}}\frac{x^{3}+5x^{2}-6x+8}{x^{4}+2x^{3}+4x^{2}+8x}dx.

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A1.2. Use the substitution x=asinhux=a\sinh u to work out the integral

0t(a2+x2)1/2dx.\int_{0}^{t}(a^{2}+x^{2})^{1/2}dx.

You may assume the formulas

2cosh2u=1+cosh2u𝑎𝑛𝑑sinh2u=2sinhucoshu.2\cosh^{2}u=1+\cosh 2u\;\;\;\mbox{and}\;\;\;\sinh 2u=2\sinh u\cosh u.

It may help to introduce vv such that t=asinhvt=a\sinh v.

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