y=-x+2√( x-1)+2 令t=√(x-1),则t≤0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不是y=-t^2+2t+1=-(t-1)^2+2≤2 值域(-∞,2]=-x+2√( x-1)+2 令t=√(x-1),则t≥0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不
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![y=-x+2√( x-1)+2 令t=√(x-1),则t≤0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不是y=-t^2+2t+1=-(t-1)^2+2≤2 值域(-∞,2]=-x+2√( x-1)+2 令t=√(x-1),则t≥0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不](/uploads/image/z/4559324-68-4.jpg?t=y%3D-x%2B2%E2%88%9A%28+x-1%29%2B2+%E4%BB%A4t%3D%E2%88%9A%28x-1%29%2C%E5%88%99t%E2%89%A40%2Cx%3Dt%5E2%2B1.y%3D-t%5E2%2B2t%2B1%3D-%28t-1%29%5E2%2B2%E2%89%A41%2C%E5%80%BC%E5%9F%9F%28-%E2%88%9E%2C1%5D+%E4%B8%BA%E4%BB%80%E4%B9%88%E4%B8%8D%E6%98%AFy%3D-t%5E2%2B2t%2B1%3D-%28t-1%29%5E2%2B2%E2%89%A42+%E5%80%BC%E5%9F%9F%28-%E2%88%9E%2C2%5D%3D-x%2B2%E2%88%9A%28+x-1%29%2B2+%E4%BB%A4t%3D%E2%88%9A%28x-1%29%2C%E5%88%99t%E2%89%A50%2Cx%3Dt%5E2%2B1.y%3D-t%5E2%2B2t%2B1%3D-%28t-1%29%5E2%2B2%E2%89%A41%2C%E5%80%BC%E5%9F%9F%28-%E2%88%9E%2C1%5D+%E4%B8%BA%E4%BB%80%E4%B9%88%E4%B8%8D)
y=-x+2√( x-1)+2 令t=√(x-1),则t≤0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不是y=-t^2+2t+1=-(t-1)^2+2≤2 值域(-∞,2]=-x+2√( x-1)+2 令t=√(x-1),则t≥0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不
y=-x+2√( x-1)+2 令t=√(x-1),则t≤0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不是y=-t^2+2t+1=-(t-1)^2+2≤2 值域(-∞,2]
=-x+2√( x-1)+2 令t=√(x-1),则t≥0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不是y=-t^2+2t+1=-(t-1)^2+2≤2 值域(-∞,2]
y=-x+2√( x-1)+2 令t=√(x-1),则t≤0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不是y=-t^2+2t+1=-(t-1)^2+2≤2 值域(-∞,2]=-x+2√( x-1)+2 令t=√(x-1),则t≥0,x=t^2+1.y=-t^2+2t+1=-(t-1)^2+2≤1,值域(-∞,1] 为什么不
t应该是-√(x-1)吧,这样的话t<=0,所以 -(t-1)^2<=-1,所以值域(-∞,1]
注意(t-1)^2取不到0
题目修改后,t=√(x-1)>=0,则y=-x+2√( x-1)+2=-(t-1)^2+2<=2是成立的,x=2时y能取到最大值2