f(x+1)
=x²-5x+4
=x²+2x+1-2x-1-5x+4
=(x+1)²-7x+3
=(x+1)²-7x-7+7+3
=(x+1)²-7(x+1)+7+3
=(x+1)²-7(x+1)+10
得出f(x+1)=(x+1)²-7(x+1)+10
令x=x+1得
因为f(x)和f(x+1)定义域相同
所以f(x)=x²-7x+10
f(x+1)
=x²-5x+4
=x²+2x+1-2x-1-5x+4
=(x+1)²-7x+3
=(x+1)²-7x-7+7+3
=(x+1)²-7(x+1)+7+3
=(x+1)²-7(x+1)+10
得出f(x+1)=(x+1)²-7(x+1)+10
令x=x+1得
因为f(x)和f(x+1)定义域相同
所以f(x)=x²-7x+10