1.

Find the 40th term of an Ap whose12th term is 47. and the 18th term is 71​

Answer»

ans: as 12TH term=47

we can WRITE it as a+11d=47-a EQ (where a is FIRST term and d is COMMON difference

similarily

we can write 18th term as a+17d=71-b eq

subtract a eq from b eq

we get d=4

a=3

40th term=a+(40-1)d

therefore 3+(39)4=3+156=159

hence 40th term is 159

thanku



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