Primitive function

curicuri

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May 30, 2019
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Hello, I ran into a problem that I would appreciate if someone could help me with.

Problem
f(x)=k-x^4 is covering an area together with the x-axis. The Area is 10 area units. k>1.
Determine k assuming k>1.

My question
My question is of a very basic sort. When I was calculating the limits for the integral --> x^4=k, I got stuck.
I started to think in terms of solving for x for equations like x^2+2x+2=0, where this one has two solutions. So when seeing x^4=k I thought to myself will this have four solutions? And if so, because the limits of the integral are only two how do I know which one to choose..
I realize in the moment of writing that I probably lack some very basic maths here.....
 
The equation x^4 = k has two real solutions, which is all that matters here. (Think about what the graph looks like.)

Yes, any number has four fourth roots, but the other two are imaginary, and can be ignored when you are dealing with curves on the real coordinate plane.

It's not that you lack basic mathematics, but that you are bringing in more advanced math where it is not needed!
 
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