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**1. Homework Statement**

State if the following is a function. If yes, write domain and range.

A. {(x,y): y=(x^1/2) ; x,y are real numbers and x>0}

B. {(x,y): y^2=x ; x is real numbers and x>0}

**2. Homework Equations**

A relation is called function if each element of the domain necessarily has a unique (one and only one) image in th range.

**3. The Attempt at a Solution**

My book says, A is a function.

Domain= Set of positive real numbers

Range= R+ - {0}

But I think that A is not a function as for say x=25, y=+5 or -5. 2 images, isnt it??? Then how can it be a function.

As about B my book and me both have the same opinion. B is not a function.

Pleas help me to figure out if I am right!