Question

5 times the 5th term of an AP is 10 times the 10th term. find the 15th term​

Answer 1

5t5=10 t10 ..... solve this

Answer 2

Answer:

15th term is 0.

Step-by-step explanation:

5t5 = 10t10

      => 5(a + (5 - 1)d) = 10(a + (10 - 1)d)

      => 5(a + 4d) = 10(a + 9d)

      => a + 4d = 2(a + 9d)

      => a + 4d = 2a + 18d

      => a = 4d - 18d

      => a = -14d......................(1)

 

So, 15th term is

T15 = a +(15 - 1)d

      = a + 14d

      = -14d + 14d  {putting the value of a in eq (1)}

      = 0 (Answer).