28x减2x=5.4

1/（x^2-7x+10)+1/(x^2-x-2)+1/(x^2+5x+4)+1/(x^2+11x+28)=[1/(x-5)-1/(x-2)+1/(x-2)-1/(x+1)+1/(x+1)-1/(x+

是这样的：x^5+x^4=x^3(x^2+x)=(x^2+x)[(x^3-1)+1]=(x^2+x)(x^3-1)+x^2+x=[x(x+1)(x-1)](x^2+x+1)+x^2+x=(x^3-x)

1)x-10=4(x-28)x-10=4x-1123x=102x=342)3(x-28)=x+56+283x-3*28=x+2*28+282x=6*28x=3*28x=843)2(1.5x-30-20

x(1+2+...+9)=x(9-8-7-...-1)x=0记得采纳啊

2x+6=5x5x-2x=63x=6x=26x-28=2x6x-2x=284x=28x=78(x-3.6)=0.8x8x-0.8x=28.87.2x=28.8x=415x-110+7x=11015x+

30%X-30%X-[(X-30%X)×20%-2]-30%X=280-(0.7X×0.2-2)-0.3X=28-0.14X+2-0.3X=280.44X=-26X=-59又11分之1

3x^2-4x=2x3x^2-6x=03x(x-2)=0x1=2x2=0

第一个：两边乘（x-3）（x-1）得x=-3第二个：两边乘（x-1）（2x-2）得x=1和x=7/6但x=1是增跟要舍去.故x=7/6再问：求检验，再答：将结果代入左边得多少，右边得多少。左边等于右边

x/(x-2)=2x/(x-3)+(1-x)/(x-5x+6)x/(x-2)=2x/(x-3)+(1-x)/(x-2)(x-3)x(x-3)/(x-2)(x-3)=2x(x-2)/(x-2)(x-3)

设x1=4-√3,x2=4+√3,是方程X^2-8X+13=0的两根所以X1^2-8X1+15=2X^4-6X^3-2X^2+18X+23=(X+1)^2*(X^2-8X+13)+10=10所以原式=

再问：请说明一下理由再答：我发的图片就是解答过程，就是将这个式子展开，展开之后再化简

x(x^2-1)+2x^2*(x+1）-3x*(2x-5)=x(3x^2-4x)-28;x^3-x+2x^3+2x^2-6x^2+15x=3x^3-4x^2-28;14x=-28.x=-2.

x/x-3减x+6/x^2-3x加3/x=[x*x-(x+6)+3(x-3)]/x(x-3)=(x^2-x-6+3x-9)/x(x-3)=(x^2+2x-15)/x(x-3)=(x+5)(x-3)/x

x/x(x-1)+2=2x/(x+1)1/(x-1)+2=2x/(x+1)x+1+2(x-1)(x+1)=2x(x-1)x+1+2x²-2-2x²-2x=0-x-1=0-x=1x=

x/(x-2)=(x-4)/(x-5)方程两边同乘(x-2)(x-5),得:x(x-5)=(x-4)(x-2)x^2-5x=x^2-6x+8x=8x/(x-3)=(x+1)/(x-1)x^2-x=x^

解题思路：集合基本关系解题过程：见附件最终答案：略

求f(x)的值域：x>0时,f(x)=log2(x),单调增,值域为R;x4,不符综合得：k的取值范围是[0,2)再问：k应当≠1吧。再答：哦，是的，要去掉这个点，因为有6个解了：k=1时，x1=-2

=x^2+10x-24+x^2+15x+56-x^2+5x+50=x^2+30x+82=4+60+82=146其实,不化简,直接代入=14*0+9*10+7*8=0+90+56=146也很简单

能不能先用（）把每个分数括起来?

X=4原式=(X-1)/(X-2)-(X-2)/(X-3)=(X-4)/(X-5)-(X-5)/(X-6)左边通分=[X^2-4X+3-X^2+4X-4]/[(X-2)(X-3)]=-1/[(X-2)