Hello,
I would really appreciate if somebody could please explain the solution to below GMAT prep question:
2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8
2^9 (correct answer)
2^10
2^16
2^35
2^37
thanks
problem with exponents
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zach,
This problem is basically a G.P problem. G.P. means Geometric Progression.
2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8
= 2 + 2(2^8 - 1)
= 2^9
Got my point, zach? By the way, if u want to know much about GP, u can do a Google-search. Otherwise, the formula for GP is -
Sn = Sum of n terms = a(r^n - 1)/(r - 1) where a = first term = 2 (here)
r = common diff = 2^2/2 = 2 (here) and n = 8.
Look I have kept the first 2 out of the series and started from the second one till end.
This problem is basically a G.P problem. G.P. means Geometric Progression.
2+2+2^2+2^3+2^4+2^5+2^6+2^7+2^8
= 2 + 2(2^8 - 1)
= 2^9
Got my point, zach? By the way, if u want to know much about GP, u can do a Google-search. Otherwise, the formula for GP is -
Sn = Sum of n terms = a(r^n - 1)/(r - 1) where a = first term = 2 (here)
r = common diff = 2^2/2 = 2 (here) and n = 8.
Look I have kept the first 2 out of the series and started from the second one till end.
Correct me If I am wrong
Regards,
Amitava
Regards,
Amitava