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How would you find the largest possible domain in real numbers for function

Anonymous User
Anonymous User
Posted 10 years ago

such as this function (x^3 + 5 x^2 + 4 x + 5)/Sqrt[x^2 + 2 x - 3]

POSTED BY: Anonymous User
4 Replies

In V10 there is also

In[1]:= FunctionDomain[(x^3 + 5 x^2 + 4 x + 5)/Sqrt[x^2 + 2 x - 3], x]

Out[1]= x < -3 || x > 1
POSTED BY: Ilian Gachevski

I want to know for what values of x there will exist real y such that y=f[x], where f is your function. Per documentation on Resolve, it does the needed quantifier elimination.

POSTED BY: Daniel Lichtblau
Anonymous User
Anonymous User
Posted 10 years ago

What is that input essentially saying?

POSTED BY: Anonymous User
Resolve[Exists[y, y == (x^3 + 5 x^2 + 4 x + 5)/Sqrt[x^2 + 2 x - 3]], Reals]

Out[10]= x < -3 || x > 1
POSTED BY: Daniel Lichtblau
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