若xy满足(x-1)^2+(y+2)^2=4求s=2x+y的最大值和最小值

问题描述:

若xy满足(x-1)^2+(y+2)^2=4求s=2x+y的最大值和最小值

xy满足(x-1)^2+(y+2)^2=4
设x=1+2cost,y=-2+2sint
s=2x+y=4cost+2sint=sqrt(20)sint(t+n)
s最大值sqrt(20)
s最小值-sqrt(20)