35x40列竖式 1/6:1/3=1/5:x 35:40=x:12

1/6:1/3=1/5:x 35:40=x:12  

1/6:1/3=1/5:x 35:40=x:12

1/6:1/3=1/5:x
解：1/6x=1/3*1/5
1/6x=1/15
x=1/15÷1/6
x=2/5
35:40=x:12
解：40x=35*12
40x=420
x=420÷40
x=10.5

4x:0.4=0.5:3/5 1/2:1/3=1/4:x 40%:x=(1+1/7):5/6 75%:(x+1)=1/4

4x:0.4=0.5:3/5
4x*3/5 =0.5*0.4
12/5*x=0.2
x=1/5*5/12
x=1/12
1/2:1/3=1/4:x
1/2*x=1/3*1/4:
1/2*x=1/12
x=1/12*2
x=1/6
40%:x=(1+1/7):5/6
8/7*x=40%*5/6
8/7*x=2/5*5/6
8/7*x=1/3
x=1/3*7/8
x=7/24
75%:(x+1)=1/4
x+1=75%*4
x+1=3
x=3-1
x=2

x/6=5/12，1/3：1/4=1/6：x,x：0.9=2.7：1.8

x/6=5/12，
x=30/12=5/2=2.5

1/3：1/4=1/6：x,
x=1/24 *3=1/8

x：0.9=2.7：1.8
x=0.9*2.7/1.8=1.35

1/3X1/5=1/15=(1/3-1/5)X1/2,1/5X1/7=1/35=(1/5-1/7)X1/2,1/7X1/9=( )=( )X( )

1/3X1/5=1/15=(1/3-1/5)X1/2,
1/5X1/7=1/35=(1/5-1/7)X1/2,
1/7X1/9=( 1/63)=(1/7-1/9 )X(1/2 )

（1/x-6）-（1/x-3）=（1/x-5）-（1/x-2）

原方程移项得：
1/(x-6) - 1/(x-5)=1/(x-3) - 1/(x-2)
左右两边分别通分得：
[(x-5)-(x-6)]/[(x-5)*(x-6)]=[(x-2)-(x-3)]/[(x-3)*(x-2)]
即：1/[(x-5)*(x-6)]=1/[(x-3)*(x-2)]
则有：(x-5)*(x-6)=(x-3)*(x-2)
即：x²-11x+30=x²-5x+6
移项化简整理得：6x=24
解得：x=4
经检验，原方程的解为：x=4

1/(x+4)+1/(x+5)=1/(x+6)+1/(x+3)

1/(x+4)+1/(x+5)=1/(x+6)+1/(x+3)
1/(x+5)-1/(x+6)=1/(x+3)-1/(x+4)
1/[(x+5)(x+6)]=1/[(x+3)(x+4)]
(x+5)(x+6)=(x+3)(x+4)
x²+11x+30=x²+7x+12
x²+11x-x²-7x=12-30
4x=-18
x=-9/2

1/（1x2）+1/（2x3）+1/（3x4）+1/（4x5）+1/（5x6）+1/（6x7）+1/（7 x8）=？

1/（1x2）+1/（2x3）+1/（3x4）+1/（4x5）+1/（5x6）+1/（6x7）+1/（7 x8）
=（1-1/2）+（1/2-1/3）+（1/3-1/4）+（1/4-1/5）+（1/5-1/6）+（1/6-1/7）+（1/7-1/8）
=1-1/8
=7/8

1/x 4 1/x 7＞1/x 5 1/x 6

不好意思，看不明白，能用汉语解释下不？

1/(x^2+x)+1/(x^2+3x+2)+1/(x^2+5x+6)+1/(x^2+7x+12)

1/(x^2+x)+1/(x^2+3x+2)+1/(x^2+5x+6)+1/(x^2+7x+12)
=1/x(x+1)+1/(x+1)(x+2)+1/(x+2)(x+3)+1/(x+3)(x+4)
=1/x-1/(x+1)+1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+1/(x+3)-1/(x+4)
=1/x-1/(x+4)
=4/(x^2+4x).

1/2｛1/3［1/4x（1/5x-1）-6］+4｝=1

1/2{1/3[1/4(1/5x-1)-6]+4}=1
{1/3[1/4(1/5x-1)-6]+4}=2
[1/4(1/5x-1)-6]+4=6
[1/4(1/5x-1)-6]=2
1/4(1/5x-1)=8
(1/5x-1)=32
1/5x=33
X=165
3/2[2/3(1/4x+1)+2]-2又1/2=2x/3
{3[2/3(1/4x+1)+2]-5}/2=2x/3
9[2/3(1/4x+1)+2]-5=4x
9[2/3(1/4x+1)+2]=4x+5
9[(1/6x+2/3)+2]=4x+5
(3/2x+6)+18]=4x+5
3/2x+24=4x+5
5X/2=19
X=38/5
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