Tright here is plainly somepoint below my teacher has actually missed once explaining this to us, so I was hoping someone could suggest me in the appropriate direction.

You are watching: Why is f not a function from r to r if

**Which $f$ is not a duty from $slrfc.orgbbR$ to $slrfc.orgbbR$ in the complying with equations, where $slrfc.orgbbR$ is the collection of genuine numbers? Explain why they are not a role.**

a. $f(x) = frac13-xsqrtx^2-1$

b. $f(x) = y$ wbelow $y=sqrtx$

c. $f(x) = x^5-7$

calculus functions

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edited Feb 14 "19 at 16:07

stressed out

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asked Feb 14 "19 at 16:00

CUPACUPA

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## 1 Answer 1

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(a) and also (b) are not functions from $slrfc.orgbbR$ to $slrfc.orgbbR$ because the set of actual numbers is not in their domains of definition.

For $a$, you have to have $x^2-1>0$ (bereason otherwise the expression under the square root will not be genuine or defined) which indicates that $x>1$ or $x.

For the second one, you must have actually that $x geq 0$ for the equivalent factor.

The last one is a function indeed. You deserve to check that it"s well-characterized and also it is characterized all over $slrfc.orgbbR$.

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answered Feb 14 "19 at 16:02

stressed outstressed out

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