Question

The sum of 5 and 9th term of an AP is 72 and the sum of 7 and 17
term is 97. Find the AP.​

Answer 1

Answer:

let AP = a, a+d , a+2d ,a+3d ,....

so 5th term = a+4d

and 9th term = a+8d

according to question

a+4d +a+8d = 72

2a + 12 d = 72 (eqs 1)

similarly a+6d + a +16 d=97

2a + 22d= 97 (eqs 2)

substracting eqs 1 by 2

it becomes -10d = -25

so ,d = 5/2

putting value of d in eqs 1

a = 21

so AP = 21, 23.5 ,26 , 28.5 ........

Answer 2

Answer:

here first number is 21 and difference between them is 5/2

Step-by-step explanation:

a+(n-1)d

as we know that ,.

a+4d+a+8d=72 --------(1)

a+6d+a+16d=97----------(2)

now subtract (1)eq from (2)eq

u will get d=5/2

and by getting d now we can find a

so, 2a+12d=72

2a+(12*5/2)=72

2a+30=72

2a=42

a=21

I hope it will help u