けんき => YSITD: 現在考慮f: R^2->R上的一條直線L g(t)=f(x+th,y+tk) ,0<=t<=1 if g diffable g(1)-g(0)=g'(p) 0<p<1 Suppose f diffable on Reigon S and L inside S (f convex) Then f(x+h,y+k)-f(x,y)=g(1)-g(0)=fx(x+ph,y+pk)h+fy(x+ph,y+pk)k => if f diffable and fx=fy=0 =>f(x+h,y+k)=f(x,y) #5c8e754b18352501bc7d8404

けんき says to YSITD

現在考慮f: R^2->R上的一條直線L g(t)=f(x+th,y+tk) ,0<=t<=1 if g diffable g(1)-g(0)=g'(p) 0<p<1 Suppose f diffable on Reigon S and L inside S (f convex) Then f(x+h,y+k)-f(x,y)=g(1)-g(0)=fx(x+ph,y+pk)h+fy(x+ph,y+pk)k => if f diffable and fx=fy=0 =>f(x+h,y+k)=f(x,y)

at Mon, Mar 18, 2019 12:26 AM