先化简,再求值:(x-1)(x-2)-3x(x+3)+2(x+2)(x-1),其中x=三分之一

2025-05-18 04:19:15
推荐回答(3个)
回答(1):

(x-1)(x-2)-3x(x+3)+2(x+2)(x-1),
=(x^2-3x+2)-(3x^2+9x)+2(x^2+x-2)
=x^2-3x+2-3x^2-9x+2x^2+2x-4
=-10x-2
=-10/3-2
=-16/3

回答(2):

原式=x²-3x+2-3x²-9x+2x²+2x-4
=-10x-2
=-10/3-2
=-16/3

回答(3):

f(x)
=(x-1)(x-2)-3x(x+3)+2(x+2)(x-1)
=x^2-3x+2-3x^2-9x+2x^2+2x-4
=-10x-2
f(1/3)=-10/3-2= -16/3