Author Topic: TUT0702 Quiz2  (Read 420 times)

Qihui Huang

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TUT0702 Quiz2
« on: October 04, 2019, 02:12:37 PM »
Determine whether the equation is exact or not

$$(e^xsin(y)-2ysin(x))-(3x-e^xsin(y))y'=0$$
Let $$M(x,y)=e^xsin(y)-2ysin(x)$$ and let $$N(x,y)=-3x+e^xsin(y)$$
Then, $$M_y(x,y)=e^xcos(y)-2sin(x)$$ $$N_x(x,y)=-3+e^xsin(y)$$
Since $$M_y \neq N_x$$
so the given differential equation is not exact.
« Last Edit: October 04, 2019, 02:18:59 PM by Qihui Huang »

Zhangxinbei

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Re: TUT0702 Quiz2
« Reply #1 on: October 04, 2019, 03:10:23 PM »
Hi Qihui! Same as you until My ?= Nx
I tried My-Nx/M, My-Nx/N and Nx-My/XM-YN, all wrong. Did he said we don't need to count it? Just to show that the equation not exact should be fine, right?
Thank you