1.

In a G.P. if the (m+n)th term is p and (m - n)th term is q, then its mth term isA. 0B. pqC. √pqD. 1/2(p+q)

Answer»

⇒ Let the first term be a and the common ratio be r.

∴ According to the question,

am+n = p.

am-n = q.

an = arn-1

am+n = a.rm+n-1

am-n = a.rm-n-1

∴ a.rm+n-1 = p.

a.rm-n-1 = n.

Multiplying above two equations we get

a2r(m+n-1+(m-n-1) = a2r(2m-2)

a2r(2m-2) = p.q

(ar)2(m-1) = p.q

∴ arm-1 =√p.q

⇒ Mth term is given by a.rm-1

∴ arm-1 =√p.q



Discussion

No Comment Found