find the 40th term of an A.P whose 12th term is 45 and 17th term is 80?
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this method can be used for any similar problems wrt ap
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Answered by
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Answer:
251
Step-by-step explanation:
consider 12th term of Ap as 1st term and
17th term as 6th term
=> a=45
n=6
an=80
to find d=?.
=> 80 = 45+ (6-1) xd
=> 80-45=5d
=> 35/5=d
=)d=7
then find a in A.P
an = a + (n-1) d
=> 45=at (12-1) X7
=> a = -32
to find :-40th term
an = -32+ (40-1) x7
= 241
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