In an A.P., if 7a,-Ila, then ap-18 – InterviewSolution

1.

In an A.P., if 7a,-Ila, then ap-18

Answer»

Given:

7a7=11a11Formula:an=a+(n-1)

a7=a+6d; a11=a+10d

Now 7(a+6d)=11(a+10d)7a+42d=11a+110d4a=-68da=-17d--------(1)

Now,a18=a+17d a18=-17d+17d.....(from (1))

Therefore a18=0

thanks

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