2)常代变在每个 △中任取一点(,nk),则Vk ~ f(Ek, nk)Aok(k =1,2,..,n)7z= f(x,y)(5i,n)
x z y o D z = f (x, y ) • ( , ) k k 2)“常代变 ” 在每个V f ( , ) (k 1,2, ,n) k k k k = 中任取一点 则
3）“近似和”nEAVe ~Zf(5k, nk)Ao kV = k=1k=14）“取极限定义的直径为2(Aok) = max(/ PP2 P,P2 E △ok)令 = max( (△ok) )z=f(x,y)1<k≤nnE f(5k, nk)Ao kV=limf(5k,7k)1-0k=1(Ek,Tk)Zok
4)“取极限” ( k ) = max P1P2 P1 ,P2 k 令 max ( ) 1 k k n = = → = n k k k k V f 1 0 lim ( , ) ( , ) k k f k ( , ) k k 3)“近似和” = n k k k k f 1 ( , )