# Talk

(7 Posts)
Celeriacacaca Fri 21-Mar-14 16:30:55

Functions

Using two number lines from 0 to 15, draw a mapping diagram to illustrate each of these functions (map each whole number)
a) x ->x+4 (->being an arrow!)
b) x ->3x
etc

Then
The inverse of the function x ->x+1 is x ->x-1. Using three number lines from 0-20, draw a mapping diagram to illustrate each of these functions as well as their inverse functions:
a)x ->4x
b)x->x+5 etc
Clearly I wasn't paying attention at school as I thought it might be y=x+4 in the first example rather than x arrow x+4 which I just don't understand. Help please?

Martorana Fri 21-Mar-14 18:17:42

No idea but if nobody's come to your rescue by 9.00 when I pick my year 8 up I'll ask him!

noblegiraffe Fri 21-Mar-14 18:28:41

Draw two number lines next to each other, from 0-15, with the numbers lined up with each other.

For x->x+4, then draw a line with an arrow from 0 on one number line to 4 on the other, 1 maps to 5 and so on.

yegodsandlittlefishes Fri 21-Mar-14 18:32:50

What noblegiraffe said. Number lines are virtical.

Brucietheshark Fri 21-Mar-14 18:37:57

The arrow thing is just a different way of saying y = x + 4 really.

Celeriacacaca Fri 21-Mar-14 18:40:56

Brilliant, thank you. I am so grateful to you all.

TeenAndTween Fri 21-Mar-14 18:41:35

I agree with noblegiraffe

That said I think I would find this even more complicated than the complicated way my DD was introduced to algebra using function boxes.

Join the discussion

Registering is free, easy, and means you can join in the discussion, watch threads, get discounts, win prizes and lots more.

Register now »