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**Mathstud28** Is it possible to set up an integral such that the region is impossible to describe?

Mr F says: Obviously it is. The example you offer below is a case in point.

$\displaystyle \int_0^1\int_1^x{f(x,y)}~dy~dx$

Because we would then have that

$\displaystyle 0\leq{x}\leq{1}$

But

$\displaystyle 1\leq{y}\leq{x}$

So basically this makes no sense yeah?

Because the only value that would make sense is x=1

Because we have that x is always less than or equal than one but always greater than or equal to one?