用夹逼定理令 A = max {a1,a2,a3,……am}A = ( A^n ) ^(1/n）≤ ( ∑ ai ^n )^(1/n) ≤ (m A^n)^(1/n) = A* m^(1/n)∵lim (n+∞) m^(1/n) = 1∴原式=A = max {a1,a2,a3,……am}
