Posted by **RAUNAK** on Saturday, February 15, 2014 at 1:26am.

AN AP has 21 term the sum of 10 ,11,12 term is 129 and sum of last 3 term is 237.find AP

- MATH -
**Steve**, Saturday, February 15, 2014 at 6:32am
T10+T11+T12 = (a+9d)+(a+10d)+(a+11d), so

3a+30d = 129

Similarly, for the last three terms,

3a+57d = 237

a=3

d=4

and the sequence is

3,7,11,...,83

## Answer this Question

## Related Questions

- Arithmetic progession - The third term of an A.P is 10times more than the second...
- Maths - The 3rd term of an AP is 10 more than the first term while the fifth ...
- math - The sum of the first 10 term of an arithmetic sequence is 145 and the ...
- math - The sum of second term and fourth term of G.P is 30 and difference ...
- maths - Given that the first term of an A.P is 7 and its 10th term is twice its ...
- arithmetic - the sum of the 3rd and the 4th term is 44 and the sum of the 10th ...
- Maths - The 5th term of an exponential sequence is 4 and of 2nd term is 35(¡)...
- Arithmetic Progression - In an AP the 6th term is half the 4th term and the 3rd ...
- Math - 1) If the sum of the first n terms of a series is Sn where Sn=2n²-n, (a)...
- math - 1) If the sum of the first n terms of a series is Sn where Sn=2n²-n, (a)...

More Related Questions