Question

Write an equation that relates x and y?
(table below)
x | y
----
1 | 1
2 | 3
3 | 7
4 | 15
5 | 31
6 | 63
7 | 127

Write an equation that relates x and y. Use your equation to find the value of y when x = 15.

Please help

Answer 1

it is not linear progression

the difference in the consecutive terms keeps doubling

Answer 2

\[\Large y= 2^x-1\]

Answer 3

ok, let me try that

Answer 4

that wouldn't work for the first set because 1 x 1 = 1, - 1 = 0.. don't I need to get 3

Answer 5

1=2^1 -1
= 2 - 1

Answer 6

still doesn't equal 3 though

Answer 7

3= 2^2 -1

7= 2^3 -1

15= 2^4 -1 ...

Answer 8

ohok

Answer 9

so y = x^2 +1

Answer 10

still doesn't work

Answer 11

nooo,

y= 2^x -1

Answer 12

when x=5
y=2^5 -1 = 2*2*2*2*2 -1

Answer 13

no because for the third on, 7, 7 = 3^2 - 1 = 8. it doesnt work

Answer 14

one*

Answer 15

when x = 3

y = 2^3 -1
= 2*2*2 -1

Answer 16

2^1 = 2
2^2 = 2*2
2^3 = 2*2*2
2^4 = 2*2*2*2
2^5 = 2*2*2*2*2
2^6 = 2*2*2*2*2*2

Answer 17

yes but that doesn't work for all of them

Answer 18

etc..