V , ., . a 1 ( x ) . D - X(x,y), Y(x,y) V. : x=rsincos, y=rsinsin, z=rcos. 25) : - . . . u1+u2+u3+...+un+... (n+1)- n- n () , , , b S = [2 ( x) -1 ( x )]dx 3) .
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