Let u = log10 x and v = logx 10 u = loge10logex , v = logexloge10dxdu = loge101⋅x1 [differentiating w.r.t x] and dxdv = loge10 . (logex)21⋅x1 Now , dvdu = dxdvdxdu = −(logex)2loge10⋅x1loge101⋅x1 = - loge101⋅x1⋅loge10x(logex)2 = - (log10)2(logx)2