find the 20 th term of the AP whose 7 th term is less than 11 th term
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To find:20th term=?
So,Let the 11thterm be x.
Then ,the 7th term be (x-1).
A/Q,
For 11th term,
N11=a+(n-1)d
11x=a+10d.................(i)
Whereas,n7=a+6d.....(I)
From eq.1 and 2,we obtain
4x=4d+7 where x is a constant
So,d=-3/4.
1st term,
n1=a+3/4
a=1/4.
Hence 20th term=a+19d=1/4+3/4=1.
So,Let the 11thterm be x.
Then ,the 7th term be (x-1).
A/Q,
For 11th term,
N11=a+(n-1)d
11x=a+10d.................(i)
Whereas,n7=a+6d.....(I)
From eq.1 and 2,we obtain
4x=4d+7 where x is a constant
So,d=-3/4.
1st term,
n1=a+3/4
a=1/4.
Hence 20th term=a+19d=1/4+3/4=1.
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