(2)(uy)'=u'y+v 证:设f(x)=u(x)v(x),△x=h,则有 f(x)=lim- f(x+h)-f(x) Ji u(x+h)v(x+h)-u(x)v(x) h->0 h->0 h lim u(x+h)-u(x) h→0 h x+8++》 =u'(x)v(x)+u(x)p'(x) 故结论成立 推论:1)(Cu)'=Cu(C为常数) 2)(ww)}=u'w+2w'w+w 》oe,y-g xlna BEIJING UNIVERSITY OF POSTS AND TELECOMMUNICATIONS PRESS 录 上页 返回 结束目录 上页 下页 返回 结束 (2) (uv) u v u v 证: 设 f (x) u(x)v(x) ,x h, 则有 h f x h f x f x h ( ) ( ) ( ) lim 0 h u x h v x h u x v x h ( ) ( ) ( ) ( ) lim 0 u (x)v(x) u(x)v (x) 故结论成立. h u x h h ( ) lim 0 u(x) v(x h) h v(x) u(x) v(x h) 推论: 1) (Cu ) 2) (uvw) Cu u vw uv w uvw 3) (loga x ) a x ln ln x ln a 1 ( C为常数 )