expressions

This topic has expert replies
Source: — Problem Solving |

Senior | Next Rank: 100 Posts
Posts: 92
Joined: Wed Mar 25, 2009 12:13 pm
Thanked: 10 times

by moutar » Sun Mar 29, 2009 2:40 pm
2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8

2+2 = 2^2
2^2 + 2^2 = 2*2^2 = 2^3
2^3 + 2^3 = 2*2^3 = 2^4

and so on

2^8 + 2^8 = 2^9 = 512

Does help if you put the options.

Master | Next Rank: 500 Posts
Posts: 148
Joined: Wed Dec 10, 2008 5:13 pm
Location: SF, CA
Thanked: 12 times

Master | Next Rank: 500 Posts
Posts: 139
Joined: Wed Oct 22, 2008 4:36 am
Thanked: 17 times

by sacx » Mon Mar 30, 2009 3:37 am
logitech gave a very good solution for this

2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8 = A

Multiply both sides by 2

2^2+2^2+2^3+2^4+2^5+2^6+2^7+2^8 + 2^9 = 2A
2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8 + 2^9 = 2A
A + 2^9 = 2A
A = 2^9
SACX

Senior | Next Rank: 100 Posts
Posts: 37
Joined: Sun Jan 25, 2009 5:34 pm

by shargaur » Tue Apr 07, 2009 5:42 pm
this is simple GP

2+ [ 2+4.....+256]
a =2 r = 2 n = 8

2 + 2[{(2^8) - 1}/(2-1)]
2 + 2(255)
512