The 7th term of an A.P. is 20 and the 13th term is 32. Find the A.P.
Answer: A
Let the first term be 'a' and the common difference be 'd'. We have \(a_7 = a + 6d = 20\) and \(a_{13} = a + 12d = 32\). Subtracting the first equation from the second gives \(6d = 12\), so \(d=2\). Substituting d=2 into the first equation gives \(a + 6(2) = 20\), so \(a + 12 = 20\) and \(a=8\). The A.P. is 8, 10, 12, ...