x^2+(4x-3x^2)-(5x-6x^2)-2,x=1/2,先化简,再求值.
问题描述:
x^2+(4x-3x^2)-(5x-6x^2)-2,x=1/2,先化简,再求值.
答
x^2+(4x-3x^2)-(5x-6x^2)-2
=x^2+4x-3x^2-5x+6x^2-2
=4x^2-x-2
=1-1/2-2
=-3/2