下面兩個極限不是應該為零嗎
為什麼會不存在呢
是因為不符合定理的假設嗎
如:非C1 和C2
若是的話可以證明給我看嗎>"<
lim [sin(x+xy-y) - (x+y)] / (x^2+Y^2)^(1/2)
(x,y)->(0,0)
lim [e^(x-y)-1-x+y] / (x^2+y^2)
(x,y)->(0,0)
Note:(first order approximation thm)
Let A be an open subset of Rn and suppose the function f:A->R is cont. diff. Let X be a point in A. Then
lim f(x+h)-[f(x)+<\/f(x), h>] / ||h|| = 0
(x,y)->(0,0)
Note:(second order approximation thm)
Let A be an open subset of Rn and suppose the function f:A->R is cont. second-order partial diff. Let X be a point in A. Then
lim f(x+h)-[f(x)+<\/f(x), h>+(1/2)<\/^2f(x)h, h>] / ||h||^2 = 0
(x,y)->(0,0)
更新1:
TO即風快客 那是倒三角型啦 只是我打不出來>"
更新2:
TO教書的 可以請你再說明 [sin(x+xy-y) - (x+y)]不等於[ f(X+H)-[f(X)]; [e^(x-y)-1-x+y]不等於[ f(X+H)-[f(X)+(grad f(A), H)] ]. 小妹不才 不會算