# St charles

The third term of an A.P is 8 and 9th term of the A.P.exceeds three times the third term by 2.find the sum of its first 19th terms.

1. 👍
2. 👎
3. 👁
1. a+2d = 8
a+8d = 3(a+2d)+2 = 26

so, 6d = 18, and d=3

Now you can find a, and answer the question.

1. 👍
2. 👎
2. a= 2
S19=551

1. 👍
2. 👎
3. a+2d=8
a+8d=3(a+2d)+2=26
6d=18
d=6
put d in a+2d= 8
a+2(3)=8
a+6=8
a=8-2
a=2
Sn= n/2[2a+(n-1)d]
=n/2[2(2)+(n-1)3]
n/2[4+3n-3]
2n+3n-3
5n+3
n=5/3

1. 👍
2. 👎
4. how in first 26 came, sir pls..can u explain me....

1. 👍
2. 👎
5. sir pls can u tell me in first how 26 came...?

1. 👍
2. 👎
6. how 26 came ??

1. 👍
2. 👎

## Similar Questions

1. ### Math

The sixth term of an A.P. is 5 times the first term and the eleventh term exceeds twice the fifth term by 3 . Find the 8th term ?

2. ### math

the 9th term of an AP is 52 while the 12th term is 70.find the sum of its 20th term

3. ### Math

The nth term of an A.P. Is 3 times the 5th term.(a)find the relationship between a and d.(b)prove that the 8th term is 5times the 4th term.

4. ### math

The 3rd term of an Arithmetic Progression is 10 more than the first term while the fifth term is 15 more than the second term. Find the sum of the 8th and 15th terms of the Arithmetic Progression if the 7th term is seven times the

1. ### math

the 6th term of A.P. is 5 times the fifth term and the 11th term is exceeds twice the fifth term by three.find the 8th term

2. ### algebra

The fifth term of an A.P exceeds twice the second term by 1.The tenth term exceeds twice the fourth term by 3. Find:1.the first term. 2.the common difference. 3.the sum of first twenty five terms.

3. ### Math

The 16th term of an AP is three times the 5th term. If the 12th term is 20 more than the 7th term, find the first term and the common difference.

4. ### Math

The first term of an A.P is -8. The ratio of the 7th term to the 9th term is 5:8. Calculate the common difference of the progression

1. ### arithmetic

in an arithmetic progression the 13th term is 27 and the 7th term is three times the second term find;the common difference,the first term and the sum of the first ten terms

2. ### math

in an AP the 10th term is 54 and 5th term is 4 times the 2nd term . Find the 1st term 'a' and common difference 'd'

3. ### Utech

The 9th term of an Arithmetic Progression is 8 and the 4th term is 20. Find the first term and the common difference.

4. ### math

The 9th term of an AP is 8 and the 4th term is 20. Find the first term and the common difference.