已知实数X,Y满足3X^2+2Y^2

问题描述:

已知实数X,Y满足3X^2+2Y^2

易知,(x²/2)+(y²/3)≤1.可设x=(r√2)cost,y=(r√3)sint.(t,r∈R,0≤r≤1).∴P=2x+y=r[(2√2)cost+(√3)sint]=(r√11)sin(t+m)≤√11.∴Pmax=√11.