From the question it I s given that,
… [equation (i)]
… [equation (ii)]
Now, subtracting equation (ii) from (i), we get,
Then, substitute the value of d is equation (i) to find a,
Therefore, nth term =
(ii) The sum of
and
terms of an A.P. is
and the
term is
. Find the A.P.
Solution:-
From the question it is given that,
a5 + a7 = 52
(a + 4d) + (a + 6d) = 52
a + 4d + a + 6d = 52
2a + 10d = 52
Divide both the side by
we get,
… equation (i)
Given,
… equation (ii)
Now subtracting equation (i) from equation (ii),
Substitute the value of d in equation (i) to find out a,
Then,
Therefore,
are A.P.