Maths C3 - Distinguishing between Functions...help?

Philip-flop

Can someone explain the answer to this question? Why is f(x) a function but g(x) isn't?? :frown:

This question is taken from the Edexcel C3 Modular Maths Textbook (Exercise 2C Q3)
Exercise2C Q3 (C3 Modular Maths).png

(edited 7 years ago)

Reply 1

sindyscape62

Original post by Philip-flop

Can someone explain the answer to this question? Why is f(x) a function but g(x) isn't?? :frown:

This question is taken from the Edexcel C3 Modular Maths Textbook (Exercise 2C Q3)
Exercise2C Q3 (C3 Modular Maths).png

To be a function every input must produce exactly one output. For g(x) an input of 4 would produce no output, so it isn't a function.

If g(x) had its domain restricted by writing

x \not=4

next to it it would be a function because now all allowed inputs do produce an output.

Reply 2

Philip-flop

Original post by sindyscape62

To be a function every input must produce exactly one output. For g(x) an input of 4 would produce no output, so it isn't a function.

If g(x) had its domain restricted by writing