Question

I an A'P the s of first 11term is 44 and that of the next 11term is 55.Find the first term and the common difference​

Answer 1

Explanation:-

S11 = 11/2(2a+10d) = 44

2a + 10d = 8. .....1

S11 = 11/2(2a+10d) = 55

2a + 10d = 10 .......2

sum of first 22 terms

= 44 + 55 = 99

S22

= 22/2(2a + 21d) = 99

2a + 21d = 9. ....3

solving eq 1 n 3

d = 1/11 a=39/11

solving eq 2 n 3

d= -1/11. a= 50/11