if 1 + 2 + 4 + 8 + 2n terms is equal to 255 then the value of n is
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8
1+2+4+8+2n=255
15+2n=255
2n=255-15
2n=240
n=240/2
n=120
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3
Answer:
Given:
1+2+4+8+ .... 2n = 255
This series is a geometric progression, hence we can use the sum of geometric progression to n terms to find the answer.
a=1 ; r = 2
Sn = a(r^n-1)/(r-1)
255 = 1(2^2n - 1)/(2-1)
» 255 = 4^n - 1
» 256 = 4^n
» n = 4
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