FP1 2016 2 Edexcel

2

(a)

We have:

\displaystyle f'(x) = \frac 9 2 x^{1/2} + \frac {25} 2 x^{-3/2}

(b)

A second approximation to \alpha is given by:

\displaystyle 12.5 - \frac {f(12.5)} {f'(12.5)} = 12.5 - \frac {0.511 \ldots} {16.1927 \ldots} = 12.5 - 0.03158\ldots

Which is 12.468 to 3 dp.

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