Question

Sum of the 1st 4 terms of an ap is 72.sum of the 1st 9 terms is also 72.then what is the 5th term of the sequence? Find the sum of the 1st five terms. Write the sequence

Answer 1

Step-by-step explanation:

let a be the first term and d be the c.d of A.P

S4=4/2(2a+3d)

72 =4a+6d

36=2a+3d. (1)

S9=9/2(2a+8d)

72*2=18a+72d

4*2=a+4d

8=a+4d. (2)

from (1)and (2)

d=-4 and a=36

Answer 2

Answer:

a is 24 and d is -4. 5th term is 8. and sum of first 5 terms are 80.