2-9分之8乘[ X除(16分之7-0.25)]=9分之2

=(x+2)/(x-1)× (x-1)^2/(x-3)(x+2)=2(x+3)/(x+3)(x-3) 你的第一个除,我换成了乘
=(x-1)/(x-3) -2/(x-3)
=1

两边乘(x+3)(x-3)
3(x+3)-(x-3)=18
3x+9-x+3=18
2x=6
x=3
经检验,x=3则分母x-3=0
是增根,舍去
所以方程无解

（1）2/(2a+3)+3/（3-2a）+（2a+15）/（4a^2-9）第一题是这样吗?实在分不清哪个是分母,都没括号啊.
2/(2a+3)+3/（3-2a）+（2a+15）/（4a^2-9）
=（2a+15）/（9-4a^2)+(2a+15）/（4a^2-9）
=0
(2)1/(x+3)+6/(x^2-9)-(x-1)/(6-2x)
=(x-3)/(x^2-9)+6/(x^2-9)-(x-1)/(6-2x)
=1/(x-3)-(x-1)/(6-2x)
=(x+1)/(2x-6)
(3)[(x+1)/(x-1)+1/(x^2+2x-1)]/(x^2)/(x-1)
=[(x+1)/(x-1)+1/(x^2+2x-1)]*(x-1)/(x^2)
=(x+1)/x^2+(x-1)/(x^4+2x^3-x^2)
=(x^3+3x^2+2x-2)/(x^4+2x^3-x^2)
(4)[1+1/(x-1)]/x/(x^2-1)
=[1+1/(x-1)]*(x^2-1)/x
=(x^2-1)/x+(x+1)/x
=x+1
(5)[(2-x)/(x-1)]/[x+1-3/(x-1)
=[(2-x)/(x-1)]/[(x^2-4)/(x-1)]
=[(2-x)/(x-1)]*[(x-1)/(x^2-4)]
=-1/(x+2)
(6)[(3x+3)/(x^2+x-2)]/[x-2+3/(x+2)-1(1-x)]
=[(3x+3)/(x^2+x-2)]/[(x^3-x^2+3)/(x+2)(x-1)]
=（3x+3)/(x^3-x^2+3)

4a^2-9分之4a^2-12a+9
=32/9a²-12a+9
=32/9×(2/3)²-12×2/3+9
=64/81-24/3+9
=145/81

x+3分之2+3-x分之2+x^2-9分之2x+18
2 2 2x+18
= --- - --- + --------
x+3 x-3 x²-9
2x-3-2x-6+2x+18
= －－－－－－－－－－
x²-9
2x+6
= ----------
(x-3)(x+3)
= 2/x-3
由于是整数,所以x-3=1 2 -1 -2
x=4 5 2 1 he是=12
2,3题自己做!别偷懒!
4 a=4.012=4 3/250
a^2+b^2+c^2-ab-bc-ca=1/2[（a-b）²+（b-c）²+（c-a）²]
=1/2（2²+1²+1²）=3

(a-4)/(a²-9)×[1+(14a-7)/(a²-8a+16)]÷[1/(a-3)]
=(a-4)/[(a-3)(a+3)]×(a²+6a+9)/(a²-8a+16)×(a-3)
=(a-4)/(a+3)×(a+3)²/(a-4)²
=(a+3)/(a-4)

119/6

4-4x+x^2分之2x^2-8除以[2(x+3)*x^2-9分之3-x]
=2(x+2)(x-2)/(x-2)^2÷[-2(x+3)*(x-3)/(x+3)(x-3)]
=2(x+2)/(x-2)÷(-2)
=-(x+2)/(x-2)

(1)
公分母是12a²b
a/2b=6a³/12a²b
b/3a²=4b²/12a²b
c/4ab=3ac/12a²b
(2)
公分母是m(2m+3)(2m-3)
1/(2m²+3m)=(2m-3)/m(2m+3)(2m-3)
2/(3-2m)=-2m(2m+3)/m(2m+3)(2m-3)
(2m+5)/(4m²-9)=m(2m+5)/m(2m+3)(2m-3)
如果不懂,请追问,祝学习愉快!

(1)、6a^2/b^4 - 1
(2)、6a - 4b + 3/2
(3)、(2x-y)^2+|y+x|=0 ==> (2x-y)^2=0 ,|y+x|=0
(2x-y)^2>=0 ==> 2x=y
|x+y|>=0 ==> x=-y
所以：x=0；y=0
[(x-y)^2+(x+y)]除2x ,x在分母中,所以：x不能为零
前后矛盾.

4a²-b²/9
=(2a)²-(b/3)²
=(2a+b/3)(2a-b/3)

当x有何值时,下列分式有意义(1)x^2-9分之2
x^2-9 ≠ 0
x ≠3 且 x≠ -3

分式a^2-3a分之1与a^2-9分之2 的最简公分母是a(a-3)(a+3)

18X(2-2/9)=18X2-18X2/9=36-2X2=32
3/4X5/2-3/2X3/4=3/4X(5/2-3/2)=3/4X2/2=3/4
2/5+(3/5)/(3/10)=2/5+3/5X10/3=2/5+2=9/4

先化简,原式=-（6/a-3)
=6/3-a
因为：-(6/3-a)>0
所以：3-a>o
a

（x+3）/（x²-9） +3/（x-3）
=（x+3）/（x-3)(x+3) + 3/（x-3）
=1/（x-3） + 3/（x-3）
=4/（x-3）
代入x=-1/2
原式=4/（-1/2-3）
=4/（-7/2）
=-8/7

分母不等于0
x^2-9=(x+3)(x-3)≠0
所以x≠-3且x≠3

1）a^2+5ab分之5b^2+ab
=b(5b+a)/[a(a+5b)]
=b/a
(2)n^2-9分之3n-n^2
=-n(n-3)/[(n+3)(n-3）]
=-n/(n+3)
通分：
y分之3x^3 5分之6xym 3分之4xy
=45x^3/15y =18xy^2m/15y =20xy^2/15y
3x^2-x分之x^2+3x
=x(x+3)/x(3x-1)
=(x+3)/(3x-1)
因为x≠0且1/3
取x=1.原式=4/2=2

x-3分之4+x2-9分之ax=x+3分之5
4/(x-3)+ax/(x²-9)=x+5/3
4+ax/(x+3)=(x-3)x+5/3(x-3)
方程有增根,所以x=3
代入得
4+3a/6=0
a=-8
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