# The sum 1 2 + 2 3 + 3 4 + 4 5 + ⋯ + 19 20 in sigma notation.

### Single Variable Calculus: Concepts...

4th Edition
James Stewart
Publisher: Cengage Learning
ISBN: 9781337687805

### Single Variable Calculus: Concepts...

4th Edition
James Stewart
Publisher: Cengage Learning
ISBN: 9781337687805

#### Solutions

Chapter F, Problem 13E
To determine

## To write: The sum 12+23+34+45+⋯+1920 in sigma notation.

Expert Solution

The sum 12+23+34+45++1920 expressed in sigma notation as i=119ii+1.

### Explanation of Solution

Definition used:

If am,am+1,...,an are real numbers and m and n are integers such that mn, then i=mnai=am+am+1+am+2++an1+an.

Calculation:

Here, the sum 12+23+34+45++1920 is the sum of 19 numbers and number is of the form ii+1, where i varies from 1 to 19.

Thus, by the above definition the sum 12+23+34+45++1920 expressed as follows.

12+23+34+45++1920=i=119ii+1

Thus, the sum 12+23+34+45++1920 expressed in sigma notation as i=119ii+1.

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