Nov-2013 · Find the 20th term of A P whose 3rd term is 7 and 7th term exceeds three times the third term by 2.
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(a+2d)=7 (1)
a+6d=3 ( a+2d) +2
a+6d=3 (7)+2 from (1)
=21+2=23 (2)
By subtracting (1) from (2) we get
4d=16
d=4
By putting the value of days in (1) we get
a= -1
Now
Term twentieth = a+19d
= -1+19×4
= -76
(a+2d)=7 (1)
a+6d=3 ( a+2d) +2
a+6d=3 (7)+2 from (1)
=21+2=23 (2)
By subtracting (1) from (2) we get
4d=16
d=4
By putting the value of days in (1) we get
a= -1
Now
Term twentieth = a+19d
= -1+19×4
= -76
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