-
The sum 9 + 16 + 25 + 36 + .... + 100 is equal to :
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- 350
- 380
- 400
- 420
- 350
Correct Option: B
As per the given question ,
Sum = 9 + 16 + 25 + 36 + 49 + 64 + 81 + 100 = 380
Second method to find the required answer with the help of formula :
Sn = 9 + 16 + 25 + ......... + 100
Sn = 3² + 4² + 5² + .......... + 10²
Sn = (1² + 2² + 3² + 4² +......+10²) – 1² – 2²
| Sn = | - 5 | |
| 6 |
| Sn = | - 5 | |
| 6 |
| Sn = | - 5 | |
| 6 |
Sn = 55 × 7 – 5 = 385 – 5 = 380
