解：a^2b=1 所以有：b=1/a^2a+b=a+1/a^2=a/2+a/2+1/a^2≥3(a/2xa/2x1/a^2)^(1/3)即：a+b≥3/2 倍的3次根号下2
a+b=(a/2)+(a/2)+b≥3(a^2b/4)^(1/3)=(3/2)×(2)^(1/3)
