导数的定义式: f(xa lim ay=lim /(xo+Ax)-f(o) Ax→0△xAx-÷0 f(oo)=in f(o+h)-f(ol=lim f(x)-f(o h->0 x→)x X-X 例1求函数y=x2在点x=2处的导数 f(2+△x)-f(2) 解f(2)=mAx0 lim (2+Ax 2-22 △ in(4+△x)=4 或f(2)=imn<(x)-f(2)=m2-22im(x+2)=4 x→ x-2 x2x-2x-2 首页上页返回 页结束铃首页 上页 返回 下页 结束 铃 例1 求函数y=x 2在点x=2处的导数 解 h f x h f x f x h ( ) ( ) ( ) lim 0 0 0 0 + −  = → 0 0 ( ) ( ) lim 0 x x f x f x x x − − = →  x x x f x f f x x  + − =  + −  =  →  → 2 2 0 0 (2 ) 2 lim (2 ) (2) (2) limlim (4 ) 4 0 = + =  → x x  lim( 2) 4 2 2 lim 2 ( ) (2) (2) lim 2 2 2 2 2 = + = − − = − −  = → → → x x x x f x f f x x x 或 x x x f x f f x x  + − =  + −  =  →  → 2 2 0 0 (2 ) 2 lim (2 ) (2) (2) lim lim( 2) 4 2 2 lim 2 ( ) (2) (2) lim 2 2 2 2 2 = + = − − = − −  = → → → x x x x f x f f x x x lim( 2) 4  2 2 lim 2 ( ) (2) (2) lim 2 2 2 2 2 = + = − − = − −  = → → → x x x x f x f f x x x 下页x f x x f x x y f x x x  + − =    =  →  → ( ) ( ) ( ) lim lim 0 0 0 0 0  导数的定义式: