已知X、Y的方程组{4x-3y=k ,2x+3y=5}的解满足x+y≦k ,求k的取值范围4x-3y=k.(1)；2x+3y=5.(2)(1)+(2)得6x=k+5,x=(k+5)/6,代入(2)式得(k+5)/3+3y=5,故y=(1/3)[5-(k+5)/3]=(10-k)/9；∴x+y=(k+5)/6+(10-k)/9=[3(k+5)+2...