x/(x+1)-x+3/(2x+4)·2x^2+4x/(x^2+6x+9)化简其中x=-2
问题描述:
x/(x+1)-x+3/(2x+4)·2x^2+4x/(x^2+6x+9)化简其中x=-2
答
(2x+1)^2-9(x+2)(x-2)+5(x+1)(x-3)
=4x^2+4x+1-9(x^2-4)+5(x^2-2x-3)
=4x^2+4x+1-9x^2+36+5x^2-10x-15
=4x^2+5x^2-9x^2+4x-10x+1+36-15
=-6x+22
=-6*(-2)+22
=12+22
=34