Question

If nine times ninth term is equal to the fifteen times fifteenth term, show that the six times twenty fourth term & Zero. ​

Answer 1

Answer:

Nine times ninth term = Fifteen times fifteenth term

9t9 = 15t15

9(a + 8d) = 5(a + 14d)

9a + 72d = 15a + 210

15a + 210d – 9a – 72d = 0

⇒ 6a + 138 d = 0

⇒ 6(a + 23 d) = 0

⇒ 6(a + (24 – 1)d) = 0

⇒ 6t24 = 0. Hence it is proved.