A particular algebra machine is programmed with a certain rule, see below for more?

Question

The algebra machine gives me 3 when I put in 2. When I put in 3 it gives me 5 and it gives me 13 when I put in 7?
Let x represent input number and y represent the resulting number, give the rule for this algebra machine?

This is for a year 7 student

Answer 1

The rule appears to be "double the number and subtract 1"

f(x) = 2x - 1

f(2) = 2(2) - 1 = 4 - 1 = 3
f(3) = 2(3) - 1 = 6 - 1 = 5
f(7) = 2(7) - 1 = 14 - 1 = 13

y = 2x - 1

Answer 2

2 => 3
3 => 5
7 => 13

How about y = 2x-1?

Put x=2, and you get 3. Put x=3, and you get 5. Put x=7, and you get 13.

What is year 7?

Answer 3

lol be more specfic next time but this is the genreal equation Y= 2x -1 lol if you want full working out email me :-) t.c
working on striaight line graphs i see lol