1. Feb 9, 2012

### Sumedh

1. The problem statement, all variables and given/known data
6(2)^(n-2) +1

then summation of above equation will be
6(2)^(n-1) + n + 2

can you please tell me how this equaton came from the first equation?

3. The attempt at a solution

the later formula is correct summation of the former

because it may look that the summation is
6(2)^(n-1) +n - 3

but by putting values of n-
6(2)^(n-1) +n - 3 is incorrect

Last edited: Feb 9, 2012
2. Feb 9, 2012

### Staff: Mentor

It doesn't. First off, these aren't equations - they are expressions. An equation is a statement that two expressions are equal, and always has an = symbol in it.

6$\cdot$2n-2 + 1 = 6$\cdot$2n-1$\cdot$(1/2) + 1 = 3$\cdot$2n-1 + 1

To show that your two expressions above aren't identically equal, let n = 2. Then 6$\cdot$2n-2 + 1 = 6 * 1 + 1 = 7.

And 6$\cdot$2n-1 + n + 2 = 6* 2 + 2 + 2 = 16.

3. Feb 9, 2012

### eumyang

I'm not sure what these expressions (and these are expressions, not equation) are. Are there any symbols missing? Can you attach an image, or retype using LaTeX?

4. Feb 10, 2012

### Sumedh

5. Feb 10, 2012

### eumyang

I get a "page is unavailable" error.

6. Feb 11, 2012