Question

1.已知实数x,y 满足2x+y≥1,求u=x+y+4x-2y的最小值.拜托了各位 谢谢

Answer 1

y>=-2x+1 (x+2)^2+(y-1)^2=u+5 u的最小值 o(-2,1)圆心的圆的最小半径 o到直线y=-2x+1的距离|1-2*2-1|/根号2^2+1=4/根号5 u+5=16/5 u=-9/5