先化简再求值 1.x(x² 3) x²(x-3)-3x(x²-x-1),其中-搜答案-搜狗做题网

1+(2x-4)/(x^2-a-2)]/[(x+3)/(x^2-1)]={1+2(x-2)/[(x-2)(x+1)]}(x^2-1)/(x+3)=[1+2/(x+1)](x+1)(x-1)/(x+3)

题目有误吧(x-x)x-1分之4(x-x)+(x-2)再问：(x方-x)(x-2)方再答：

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

（3x/x-1-x/x+1)*x^2-1/2x,其中x=-3=(3x^2+3x-x^2+1)/(x-1)(x+1)*(x+1)(x-1)/2x=(2x^2+x+1)/2x=x+1/2+1/2x=-3+

=x+(3x-2x)+(5x-4x)+……+(101x-100x)=x+x+……+x=51x=51×2/51=2

x²(3-x)+x(x²-2x)+1=3x²-x³+x³-2x²+1=x²+1=3+1=4

3x^3-[-x^2-2(x-x^6)]=3x^3+x^2+2(x-x^6)=3x^3+x^2+2x-2x^6x=-1原式=-3+1-2-2=-6

（x+2/x²-2x-x-1/x²-4x+4）÷x-4/x={(x+2)(x-2)/[x(x-2)²]-x(x-1)/[x(x-2)²]}·x/(x-4)={(

再问：(x加2）吗？再答：什么？再问：第一个括号里的是x加几

小括号内先通分：分母为x平方-4,分子为3x平方+6x,另一个是x平方-2x化简：{x²-4分之2x²+8x}÷x²-4分之2x结果=x+4

=[(x+3)(x-3)-7]/(x-3)2(x-3)/(x²-8x+4²)=2(x²-4²)/(x-4)²=2(x+4)(x-4)/(x-4)&su

[x^2-9]/[x^2+6x+9]】×【[3x^3+9x^2]/[x^2-3x]】=(x+3)(x-3)/(x+3)²*(3x²(x+3)/x(x-3))=(x-3)/(x+3)

∵|x|=3∴x=3或x=-33x²+(2x²-3x)-(-2x+x²)=3x²+2x²-3x+2x-x²=4x²-x当x=3时,

3x^2-[7x^2-2(x^2-3x)-2x]=3x^2-[7x^2-2x^2+6x-2x]=3x^2-[5x^2+4x]=3x^2-5x^2-4x=-2x^2-4x=-2x(-2)^2-4x(-2

x^3-2x^2+4x/x^2-4x+4÷x^2-2x+4/x-2=x(x²-2x+4)/(x-2)²÷(x-2)/(x²-2x+4)=x(x²-2x+4)/(

[3x/(x+2)-x/(x-2)]÷2x/(x^2-4)分子分母同时乘以x²-4=[3x(x-2)-x(x+2)]/2x=(3x²-6x-x²-2x)/2x=(2x&#

求值9x+6x

原式=9x+6x2-3x+2x2=8x2+6x当x=-2时原式=8×（-2）2+6×（-2）=32-12=20．

（x²-5-4x）-x（x²＋x-1）=x^2-5-4x-x^3-x^2+x=-x^3-3x-5当x=-1时-x^3-3x-5=-(-1)-3*(-1)-5=1+3-5=-1

6x(x²-x+1)-(2x+3)(3x-2)=6x³-6x²+6x-(6x²-4x+9x-6)=6x³-6x²+6x-6x²-5

(x-4)(x-2)-(x-1)(x-3)=x²-6x+8-x²+4x-3=-2x+5当x=-5/2时原式=-2*(-5/2)+5=5+5=10