If 6th and 14th terms of an A.P. are 29 and 69 respectively, then its 21st term is

Question

If 6th and 14th terms of an A.P. are 29 and 69 respectively, then its 21st term is

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Quinn 4 months 2022-01-06T00:20:49+00:00 1 Answer 0 views 0

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    2022-01-06T00:22:44+00:00

    Answer:

    149

    Step-by-step explanation:

    nth term = a+(n-1)d

    6th term = a+(6-1)d=29

                      a+(6-1)d=29

                      a+5d=29 __________eq1

                     

    14th term = a+(14-1)d=69

                      a+(14-1)d=69

                       a+13d=69__________eq2

    eq2-eq1

    a+13d-(a+5d)=69-29

    a+13d-a-5d=40

    8d=40

    d=8

    putting d=8 in eq1

    a+5(8)=29

    a+40=29

    a=29-40

    a= -11

    21th term = a+(21-1)d

                    =-11+(20)8

                     = -11+160

                      =149

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