Question

In an AP with 20 terms the middle term are 49 and 53 . then find last term​

Answer 1

Step-by-step explanation:

GIVEN:-

n=20

l=?

middle terms=A10=49

=A11=53

A10=a+9d------------(1)

A11=a+10d------------(2)

by eliminating method

a+ 9d=49

a+10d=53

________

-d= -4

d=4

------

substitute d value in eq^n (1)

49=a+9d

49=a+9(4)

49=a+38

49-38=a

11=a

a=11

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Now,finding last term:-

an=a+(n-1)d

=11+(20-1)4

=11+(19)4

=11+76

=87

therefore,last term an=(l)=87

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