Question

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

Answer 1

Step-by-step explanation:

• Given: 9(t9)=15(t15)
• we know that , tn=a+(n-1)d
• Therefore, from given
• 9(a+8d)=15(a+14d)
• 9a+72d=15a+210d
• 15a-9a+210d-72d=0
• 6a+138d=0...........(1)
• NOW, ,
• 6(t24)=6(a+23d)
• =6a+138d
• from equation (1)
• 6(t24)=0 is proved