求值域 y=(x²-8x+15)/(x²-x-6)

分类: 作业答案 • 2022-03-19 21:07:33

问题描述：

答

y=(x²-8x+15)/(x²-x-6)=(x-3)(x-5)/(x-3)(x+2)=(x-5)/(x+2) (x≠3)
=1-7/(x+2) (x≠3)
∴y≠1且y≠(3-5)/(3+2)=﹣2／5
∴值域是﹛y|y∈R且y≠1且y≠﹣2／5﹜