作业帮f（x）=x²-1,g（x）=x-1＞0,x＞0 2-x＜0,x＜0,求f[g(2)] g[f(2)],f[g(x)],g[f(x)]
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![f（x）=x²-1,g（x）=x-1＞0,x＞0 2-x＜0,x＜0,求f[g(2)] g[f(2)],f[g(x)],g[f(x)]](/uploads/image/z/15130963-19-3.jpg?t=f%EF%BC%88x%EF%BC%89%3Dx%26%23178%3B-1%2Cg%EF%BC%88x%EF%BC%89%3Dx-1%EF%BC%9E0%2Cx%EF%BC%9E0+2-x%EF%BC%9C0%2Cx%EF%BC%9C0%2C%E6%B1%82f%5Bg%282%29%5D+g%5Bf%282%29%5D%2Cf%5Bg%28x%29%5D%2Cg%5Bf%28x%29%5D)
f（x）=x²-1,g（x）=x-1＞0,x＞0 2-x＜0,x＜0,求f[g(2)] g[f(2)],f[g(x)],g[f(x)]
f（x）=x²-1,g（x）=x-1＞0,x＞0 2-x＜0,x＜0,求f[g(2)] g[f(2)],f[g(x)],g[f(x)]
f（x）=x²-1,g（x）=x-1＞0,x＞0 2-x＜0,x＜0,求f[g(2)] g[f(2)],f[g(x)],g[f(x)]
g(2)=2-1=1
f(g(2))=f(1)=0
f(2)=2²-1=3
∴g(f(2))=g(3)=3-1=2
当x>0时 f(g(x))=(x-1)²-1=x²-2x
当x0
∴x>1或x