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secondary 4 | E Maths
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Hi can someone pls explain why ans for 1b is 2^n-1+2n-1?
Date Posted: 5 years ago
Views: 258
Look at the powers of 2.
0, 1, 2, 3, ...
Difference between terms is 1. First term is 0, so ‘zero’th term is -1. So the formula for this sequence is n - 1.
Look at the other sequence.
1, 3, 5, 7, ...
Difference between terms is 2. ‘Zero’th term is -1. So 2n - 1.
Put all together and you get 2^(n - 1) + 2n - 1.
0, 1, 2, 3, ...
Difference between terms is 1. First term is 0, so ‘zero’th term is -1. So the formula for this sequence is n - 1.
Look at the other sequence.
1, 3, 5, 7, ...
Difference between terms is 2. ‘Zero’th term is -1. So 2n - 1.
Put all together and you get 2^(n - 1) + 2n - 1.
nabanita I think you mean why that's the answer for c) instead of b) which you have written
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