You cannot add exponents when doing addition, but only during multiplication. Therefore: (2^2)(2^2) = 2^4 but (2^2)+(2^) != 2^4 As far as I know, you simply have to work out this problem, there is no quick solution - 2+2+4+8+16+32+64+128+256 = 512 = 2^9

Another way to solve the problem. 2 + 2 + 2^2 + 2^3 + 2^4 .... + 2^8. = 4 + 2^2 + 2^3 .... = 2 (2^2) + 2 ^ 3 + 2^4 + 2^5... + 2^8 = 8 + 2^3 + 2^4 ... + 2^8 = 2(2^3) + 2^4 + ....2^8 trend continues. and finally you will be left with 2(2^8) = 2^9 Which is answer A

arzanr wrote:You cannot add exponents when doing addition, but only during multiplication. Therefore: (2^2)(2^2) = 2^4 but (2^2)+(2^) != 2^4 As far as I know, you simply have to work out this problem, there is no quick solution - 2+2+4+8+16+32+64+128+256 = 512 = 2^9 There is a quick solution: If you multiply both side with 2 LEFT side = ANSWER 2 x LEFT SIDE = 2 x ANSWER you will realize that left side can also be arranged as: ANSWER + 2^9 = 2x ANSWER so ANSWER = 2^9

there's another quick soln:---2 + (2 + 2^2 + 2^4 +......) the nom in bracket can be taken as sum of GP(geo metric progr.) now the sumof terms of GP is: a(r^n-1)/ (r-1) where a=first term which is 2 in this case r= general ration or diff so, answer will be sum + first term i.e 2 2 + 2(2^8-1)/2-1 2 + 2 x 255 2 + 510 512 2^9

abhijeetsinghai wrote:there's another quick soln:---2 + (2 + 2^2 + 2^4 +......) the nom in bracket can be taken as sum of GP(geo metric progr.) now the sumof terms of GP is: a(r^n-1)/ (r-1) where a=first term which is 2 in this case r= general ration or diff so, answer will be sum + first term i.e 2 2 + 2(2^8-1)/2-1 2 + 2 x 255 2 + 510 512 2^9 No need of solving it. 2 + 2(2^8-1)/2-1 = 2 + 2^9 -2 = 2^9 is the answer.

Really good one... Logitech u r cool logitech wrote:arzanr wrote:You cannot add exponents when doing addition, but only during multiplication. Therefore: (2^2)(2^2) = 2^4 but (2^2)+(2^) != 2^4 As far as I know, you simply have to work out this problem, there is no quick solution - 2+2+4+8+16+32+64+128+256 = 512 = 2^9 There is a quick solution: If you multiply both side with 2 LEFT side = ANSWER 2 x LEFT SIDE = 2 x ANSWER you will realize that left side can also be arranged as: ANSWER + 2^9 = 2x ANSWER so ANSWER = 2^9