Question

The sum of 5th and 11th terms of an AP is 38 and the sum of the 6th and 13th term is 47, find the first three terms of the AP​

Answer 1

Answer:

Given, sum of the 5th and 7th term is 52.

∴a+4d+a+6d=52

⇒2a+10d=52⟶(1)

And, the 10th term is 46.

∴a+9d=46

multiplying it by 2 we get,

2a+18d=92⟶(2)

Solving equations (1) and (2) we get,

8d=40

⇒d=5

Substituting the value of d in (1) we get,

2a+(10×5)=52

⇒2a=52−50

⇒a=1

Therefore, the required A.P. is,

1,6,11,16,21,26,31

Answer 2

Step-by-step explanation:

Given, sum of the 5th and 7th term is 52.

∴a+4d+a+6d=52

⇒2a+10d=52⟶(1)

And, the 10th term is 46.

∴a+9d=46

multiplying it by 2 we get,

2a+18d=92⟶(2)

Solving equations (1) and (2) we get,

8d=40

⇒d=5

Substituting the value of d in (1) we get,

2a+(10×5)=52

⇒2a=52−50

⇒a=1