Hello,(adsbygoogle = window.adsbygoogle || []).push({});

My calculus book is confusing and I am pretty sure this is an error. It describes a function as one where one distinct input will have one and only one distinct output. Fair enough.

The next example is output of f(x) = square root (x) when input is 25!

Clearly, this is not a function! This relation (obviously) does not result in a unique output for every unique input, right? square root (25) = +5 and -5.

Or am I missing something in function defs. The book does not even consider the negative value of a square root operation.

That's what I get for buying the idiot's guide...

Please let me know if I am missing something here.

Thanks,

Luca

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Basic question about functions

**Physics Forums | Science Articles, Homework Help, Discussion**