2n-1 s(x)=∑「m r2-1x2n2dy=②2) ∑ x2+2 (2 -2)2 x(2-+)2=3,款2n= lim s()=lim x2+2 3. 2 = − − = 1 0 2 2 ) 2 2 1 ( ) ( n x n n x dx n s x = − = 1 2 1 ) 2 ( n n n x ) ) 2 ( 1 ( 1 2 = n= x n x ) 2 1 ( 2 2 − = x x x ) 2 ( 2 − = x x , (2 ) 2 2 2 2 x x − + = 2 2 2 1 (2 ) 2 lim x x x − + = → − lim ( ) 1 s x x→ − = 3, 3. 2 2 1 1 = − n= n n 故