实数X.Y满足X²-2X-4Y=5,计T为X-2Y,求T的取值范围

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实数X.Y满足X²-2X-4Y=5,计T为X-2Y,求T的取值范围实数X.Y满足X²-2X-4Y=5,计T为X-2Y,求T的取值范围实数X.Y满足X²-2X-4Y=5,计

实数X.Y满足X²-2X-4Y=5,计T为X-2Y,求T的取值范围
实数X.Y满足X²-2X-4Y=5,计T为X-2Y,求T的取值范围

实数X.Y满足X²-2X-4Y=5,计T为X-2Y,求T的取值范围
y=(x²-2x-5)/4
t=x-2(x²-2x-5)/4
=(-x²+4x+5)/2
=[-(x-2)²+9]/2
-(x-2)²