1多元变量求最值班级____________姓名___________1.若正实数yx,满足141yx,则xy的最小值是____________2.若1410,0yxyx且,则yx的最小值是_________________3.已知正实数yx,满足42yx,则yxy12的最小值为__________4.若022,0,0xyyxyx,则yx的最小值是______________5.已知正实数yx,满足42yxxy,则yx的最小值为___________6.已知x是正实数,且22xxy,则212yx的最小值为___________7.设1,,22baRba,则ba的最小值是_____________8.已知正实数yx,满足422xyyx,则yx的最大值是______________9.已知,1,nmnm则nmnm22的最小值是____________10.已知正数a,b满足a+b=1,则ab的取值范围是____________,1abab的最小值是________11.已知正实数ba,满足8abba,则ba的最小值是__________,ab的最大值是________12.已知:2222,(,0)xyamnbab,则mx+ny的最大值是_____________13.已知)(,0,033yxkxyyxyx若不等式恒成立,则实数k的最大值为____________14.已知yx,为正数,则yxyyxx22的最大值为_____________215.若11121,0,0bbaba且,则ba5的最小值为___________16.已知正实数yx,满足1yx,则1222yyxx的最小值是____________17.已知2,0yxyxyx且满足,实数,则yxyx132的最小值是__________18.若不等式2222xyxycxyxyxyxy对任意正数x,y恒成立,则常数c=_________19.设1),2,2(,xyyx,则229944yx的最小值为__________20.已知正数abcbacba4,,满足,则cba的最小值为___________21.已知正数10111,1,,cbacbacba满足,则abc的最小值为____________22.已知yx,是正数,且满足4)1(yxxy,则)1)((xyx的最小值为___________23.设0,,cba,且4)(bccbaa,则cba2的最小值是_________________24.已知实数zyx,,满足3,1222zyxzyx,则xyz的最大值为_____________25.若第一象限内的动点),(yxP满足xyRxyyx,123211,则以P为圆心,R为半径且面积最小的圆的方程为_________________________