Question

f(x+1)=x^2-2x,则f(x)= 过程？

Answer 1

f(x+1)=x²-2x
令t=x+1，则：x=t-1
则f(t)=(t-1)²-2(t-1)
=t²-2t+1-2t+2
=t²-4t+3
用x取代t，得：f(x)=x²-4x+3

Answer 2

令t=x+1,则f(t)= (t-1)^2-2*(t-1)=t^2+1-2t-2t+2=t^2-4t+3
所以f(x)=x^2-4x+3
好久不做题了，应该没错。呵呵。

Answer 3

把后面配写成（x-1）平方-1后用x-1取代x
就变成f（x)＝（x-2）平方-1
打开就是

Answer 4

f(x+1)=x^2-2x,
令x+1=t
则x=t-1
f(t)=(t-1)^2-2(t-1)=t^2-4t+3
即 f(x)=x^2-4x+3

Answer 5

x+1=t x=t-1
f(t)=f(x+1)=xx-2x=(t-1)^2-2(t-1)=t^2-4t+3
f(x)=x^2+4x+3