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20 questions
What is the formula to find the sum of 'n' terms of an A.P. with first term 'a' and common difference 'd'
Sn = n/2 { 2a + (n+1)d}
Sn = n/2 { a + (n+1) d}
Sn = n/2 { 2a + (n-1)d}
Sn = n/2 { a + (n-1)d}
The sum of the first 20 natural numbers is
110
170
190
210
If the first term of an AP is -5 and the common difference is 2, then the sum of the first 6 terms is
0
5
6
15
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