10.3 The Newton-Raphson Method
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In a precision optics experiment, the refractive index μ \mu\,μ of a specific polymer varies with the distance x x\,x from the optical center of a lens according to the model μ=7+2ex2,x≥0\mu = \sqrt{7 + 2e^{x^2}}, \quad x \ge 0μ=7+2ex2​,x≥0

a.

Find dμdx\displaystyle \frac{d\mu}{dx}dxdμ​, giving your answer in its simplest form.

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b.

A light ray intersects the curve at a point P P\,P with xxx-coordinate β\betaβ. It is determined that the tangent to the curve at P P\,P passes through the origin.

Show that x=βx = \betax=β is a root of the equation (2x2−2)ex2−7=0(2x^2 - 2)e^{x^2} - 7 = 0(2x2−2)ex2−7=0

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c.

Hence show that β \beta\,β lies between 1.2 and 1.3.

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d.

Show that the Newton-Raphson formula for the equation in part (b) can be written as xn+1=4xn4−2xn2+2+7e−xn24xn3x_{n+1} = \frac{4x_n^4 - 2x_n^2 + 2 + 7e^{-x_n^2}}{4x_n^3}xn+1​=4xn3​4xn4​−2xn2​+2+7e−xn2​​

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e.

Using the Newton-Raphson formula with x1=1.3x_1 = 1.3x1​=1.3, find to 4 decimal places the value of (i) x3x_3x3​ (ii) β\betaβ

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10.3 The Newton-Raphson Method Questions

Practise Edexcel A Level Maths 10.3 The Newton-Raphson Method with exam-style questions for A Level Maths. 23 questions, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.

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10.3 The Newton-Raphson Method Questions

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