若正数a,b,c,d满足a+b+c+d=1,求1/(3a+2)+1/(3b+2)+1/(3c+2)+1/(3d+2)的最小值.1/(3a+2)的意思是(3a+2)分之一.其他以此类推.请用高中数学不等式选讲内容解答,

问题描述:

若正数a,b,c,d满足a+b+c+d=1,求1/(3a+2)+1/(3b+2)+1/(3c+2)+1/(3d+2)的最小值.
1/(3a+2)的意思是(3a+2)分之一.其他以此类推.请用高中数学不等式选讲内容解答,

3a+2+3b+2+3c+2+3d+2=3(a+b+c+d)+8=3+8=11≥4[(3a+2)(3b+2)(3c+2)(3d+2)]^(1/4)所以1/[(3a+2)(3b+2)(3c+2)(3d+2)]^(1/4)≥4/11而1/(3a+2)+1/(3b+2)+1/(3c+2)+1/(3d+2)≥4{1/[(3a+2)(3b+2)(3c+2)(3d+2)]^(1/4)...