If an A.P. is such that a4a7=23, find a6a8
a4a7=23 [Given] ⇒a+3da+6d=23⇒3a+9d=2a+12d ⇒a=3d ...... (i) a6a8=a+5da+7d ⇒3d+5d3d+7d [∵3d from (i)] ⇒8d10d⇒45 ∴a6a8=45