Question

3rd term of an ap is 1/5 and 5th term of ap is 1/3 what is sum of first 15 terms

Answer 1

Try googling it I’m sure you will find the answer

Answer 2

Answer:

Step-by-step explanation:

last term = first term + (n-1)d

considering first 3 terms

1/5 = a + (3-1)d = a + 2d

a = 1/5 - 2d .................. equation 1

considering first 5 terms

1/3 = a + (5-1)d = a + 4d

a = 1/3 - 4d .................. equation 2

on comparing both equations

1/5 - 2d = 1/3 - 4d

1/5 - 1/3 = 2d - 4d

-2/15 = -2d

d = 1/15

a = 1/15

sum of first 15 terms

S(n) = n/2[2a+(n-1)d]

Sn = 15/2[2/15+14/15]

Sn = 15/2[16/15]

Sn = 8