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IAL 2022 Jan Q9

A Level / Edexcel / P4

IAL 2022 Jan Paper · Question 9

题目

Problem

(a) Find the derivative with respect to yy of

1(1+2lny)2\frac{1}{(1+2\ln y)^2}
(2)

(b) Hence find a general solution to the differential equation

3cosec(2x)dydx=y(1+2lny)3y>0π2<x<π23\cosec(2x)\frac{dy}{dx}=y(1+2\ln y)^3 \qquad y>0 \qquad -\frac{\pi}{2}<x<\frac{\pi}{2}
(4)

(c) Show that the particular solution of this differential equation for which y=1y=1 at x=π6x=\dfrac{\pi}{6} is given by

y=eAsecx12y=e^{A\sec x-\frac{1}{2}}

where AA is an irrational number to be found.

(5)
题目中文翻译

(a) 求

1(1+2lny)2\frac{1}{(1+2\ln y)^2}

关于 yy 的导数。

(b) 进而求微分方程

3cosec(2x)dydx=y(1+2lny)3y>0π2<x<π23\cosec(2x)\frac{dy}{dx}=y(1+2\ln y)^3 \qquad y>0 \qquad -\frac{\pi}{2}<x<\frac{\pi}{2}

的通解。

(c) 证明满足 x=π6x=\dfrac{\pi}{6}y=1y=1 的该微分方程特解为

y=eAsecx12y=e^{A\sec x-\frac{1}{2}}

其中 AA 是一个待求的无理数。

解答