Question

The difference of 4th and 10th term of an A.P. is 36 and the difference of 7th and 15th terms is 48. Find the first term and the common difference of the A.P.​

Answer 1

Answer:

Step-by-step explanation:

Let a be the first term and d be the common difference of the A.P.

Now, 4  

th

 term of the A.P. = a+3d=22 ... (1)

Also, 15  

th

 term of the A.P. = a+14d=66 ... (2)

Subtracting (1) from (2), we get

11d=44⟹d=4

Substituting value of d in (1), we have

a+12=22⟹a=10

Sum of first 8 terms =  

2

n

​

(2a+(n−1)d)=  

2

8

​

(20+(8−1)4)=192

Hence, the first term, the common difference and the sum upto 8 terms are 10,4 and 192 respectively