Question

Find whether 55 is a term of the ap:7,10,13...or not.if yes find which term it is?

Answer 1

a=7

d=3

therefore, ATQ; An=55

                          a+(n-1)d=55

                          7+(n-1)3=55

                          (n-1)3=55-7

                          (n-1)=48/3

                          n-1=16

                       => n=17

therefore, the 17th term is 55

Answer 2

a=7

d=3

an=55

•°• an=a+(n-1)d

55= 7+(n-1)3

48=(n-1)3

16=n-1

17= n

•°• 55 IS 17th term of given AP.

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