Question

If $p^{th}$ term of an AP is q, and its $q^{th}$ term is p, then what is the common difference ?

• A. -1
• B. 0
• C. 2
• D. 1

Answer 1

Answer: (A)

Let first term and common difference of an AP are a and d respectively.
Its $p^{t}h$ term = a + (p - 1) d = q ...(i)
and $q^{th}$ term = a + (q - 1) d = p ...(ii)
Solving Eqs. (i) and (ii), we find a = p + q -1, d = -1