先化简再求值1-X 2

原式=[1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)]×(x+4)(x+5)=[1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+1/(x+3)-1/(x

:(1)2x2-5x+x2+4x,其中x=-3=3x²-x=3x(-3)²+3=27+3=30(2)(3x2-xy-2y2)-2(x2+xy-2y2),其中x=6,y=-1=3x&

原式=(x+1)²/(x+2)÷(x+1)(x-1)/(x-1)-x/(x+2)=(x+1)²/(x+2)÷(x+1)-x/(x+2)=(x+1)/(x+2)-x/(x+2)=(x

⑴原式=(2a1)(2a1-2)3=(2a1)(2a-1)3=4a²-13=4a²2=4*22=10⑵原式=(x1)xx-(x1)(x-1)=(x1)(x-x1)x=2x1=-11

原式=9x+6x2-3x+2x2=8x2+6x，当x=-1时，原式=8×（-1）2+6×（-1）=8-6=2．

原式=-x2-y2-3xy-x2+y2=-2x2-3xy，当x=-1，y=2时，原式=-2×（-1）2-3×（-1）×2=4．

原式=[x+2x(x-2)-x-1(x-2)2]÷x2-16x2+4x=[x2-4x(x-2)2-x2-xx(x-2)2]÷x2-16x2+4x=x-4x(x-2)2•x(x+4)(x+4)(x-4)

x²+2x+1=10（x+1)²=10x+1=3或x+1=-3所以x=2或x=-4【（x²+4)/x-4】÷【（x²-4)/(x²+2x)】=【（x&

3（x2-2x-1）-4（3x-2）+2（x-1）=3x2-6x-3-12x+8+2x-2=3x2-16x+3．当x=-3时，原式=3×（-3）2-16×（-3）+3=27+48+3=78．

原式=(x-1)(x+1)/(x+2)*(x+2)/x-1=x+1然后代入数值即可很高兴为您解答,【学习宝典】团队为您答题.请点击下面的【选为满意回答】按钮,

(x^2-2x+1)/(x^2-1)+1/(x+1)=(x-1)^2/(x+1)(x-1)+1/(x+1)=(x-1)/(x+1)+1/(x+1)=x/(x+1)=1-根2分之一

x²-3x+2=0(x-1)(x-2)=0因为分母x-1≠0所以x-2=0x=2原式=x(x-1)/(x-1)*(x+1)(x-1)/(x-1)²=x*(x+1)/(x-1)=2*

[(x-4)/(x^2-1)]÷[(x^2-3x-4)/(x^2+2x+1)]+1/(x-1)=[(x-4)/(x-1)(x+1)]÷[(x+1)(x-4)/(x+1)^2]+1/(x-1)=[(x-

解原式=[(x+1)²/(x+2)]×[(x-1)/(x-1)(x+1)]-1/(x+2)=[(x+1)²/(x+2)]×1/(x+1)-1/(x+2)=(x+1)/(x+2)-1

详细而规范的解答过程看图,明白就采纳,

原式=2x²-4x²+3x-3x+7+1=-2x²+8=-2*2²+8=-8+8=0

①x2+3=3（x+1）x2-3x=0x（x-3）=0解得：x1=0，x2=3．②4（3x+1）2=25（x-2）24（3x+1）2-25（x-2）2=0（6x+2+5x-10）（6x+2-5x+10

x2+y2+4x-8y+20=0(x+2)^2+(y-4)^2=0所以x=-2y=4(x-y)2(x+y)2-(x2+y2)2=(x^2-y^2)^2-(x^2+y^2)^2=2x^2*(-2y^2)

原式=2x2-2xy-6x2+9xy-2x2+2x2-xy+y2=-2x2+5xy+2y2，当x=-1，y=-2时，原式=-2+10+8=16．