This was a problem on a final test I took this april in Reykjavík University and I whould be greatful if you could help me with it.(adsbygoogle = window.adsbygoogle || []).push({});

1. The problem statement, all variables and given/known data

Let f(x,y)=2x*cos(y^4) be a function and let D be area in R^2 defined by 0≤x≤1 and x^(2/3)≤y≤1.

Calculate the double integer:

∫∫f(x,y)dA

2. Relevant equations

3. The attempt at a solution

∫dx∫2x*cos(y^4)dy

I have tried to use substitution but that doesn´t lead me anywhere.

I also tried to solve it this way...

∫dy∫2x*cos(y^4)dx which leads to...

∫dy*(x^2*cos(y^4)) and when I add in for x...

∫dy*cos(y^4) and if I use substitution now I will get...

1/4*∫cos(u)du and the final answer isn´t sufficient...

1/4*(sin(1)-sin(x^(8/3)))

I would be very greatful if you could help me...

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# Calculate double integer

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