f(x)={x²-x,x≤0 {1+2lgx(x>0),若f(x)=2,则x=
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![f(x)={x²-x,x≤0 {1+2lgx(x>0),若f(x)=2,则x=](/uploads/image/z/15026299-43-9.jpg?t=f%28x%29%3D%7Bx%26%23178%3B-x%2Cx%E2%89%A40+%7B1%2B2lgx%EF%BC%88x%EF%BC%9E0%EF%BC%89%2C%E8%8B%A5f%EF%BC%88x%EF%BC%89%3D2%2C%E5%88%99x%3D)
f(x)={x²-x,x≤0 {1+2lgx(x>0),若f(x)=2,则x=
f(x)={x²-x,x≤0 {1+2lgx(x>0),若f(x)=2,则x=
f(x)={x²-x,x≤0 {1+2lgx(x>0),若f(x)=2,则x=
f(x)= {x²-x,x≤0
1+2lgx(x>0),
(1)如果x²-x=2,可得x=-1或者x=2,此时的条件是x≤0,因此f(-1)=2;
(2) 如果1+2lgx=2,可得x=根号10,此时条件x>0,因此f(根号10)=2
综合有:若f(x)=2,则x=-1或根号10.
x≤0时;
x²-x=2
x²-x-2=0
(x+1)(x-2)=0
∴x=-1
x>0时;
1+lgx=2
lgx=1;
x=10;
综上,x=-1或x=10