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8 tháng 6 2015

\(\frac{10x-5}{6}+\frac{x+3}{4}\ge\frac{7x+3}{2}-\frac{12-x}{3}\)

<=>\(\frac{2\left(10x-5\right)}{12}+\frac{3\left(x+3\right)}{12}\ge\frac{6\left(7x+3\right)}{12}-\frac{4\left(12-x\right)}{12}\)

<=>2(10x-5)+3(x+3)\(\ge\)6(7x+3)-4(12-x)

<=>20x-10+3x+9\(\ge\)42x+18-48+4x

<=>23x-1\(\ge\)46x-30

<=>23x-46x\(\ge\)-30+1

<=>-23x\(\ge\)-29

<=>x\(\le\)\(\frac{29}{23}\)

Vậy S={x I x\(\le\frac{29}{23}\)}

7 tháng 6 2015

40x-20+6x+18 (lớn hơn hoặc bằng ) 84x+36 - 96+8x
rồi giải bt @@:
x (bé hơn hoặc bằng) -(29:23)

 

 

5 tháng 2 2020

hiu hiu

22 tháng 4 2020

help me !!!!

30 tháng 4 2020

tui cx nghĩ đề lỗi.chứ ko tự làm rồi

18 tháng 8 2020

1. \(\frac{7x-1}{6}+2x=\frac{16-x}{5}\)

\(\Leftrightarrow5\left(7x-1\right)+60x=6\left(16-x\right)\)

\(\Leftrightarrow35x-5+60x=96-6x\)

\(\Leftrightarrow95x-5=96-6x\)

\(\Leftrightarrow95x+6x=96+5\)

\(\Leftrightarrow101x=101\)

\(\Leftrightarrow x=1\)

2. \(\frac{10x+3}{12}=1+\frac{6+8x}{9}\) 

\(\Leftrightarrow3\left(10x+3\right)=36+4\left(6+8x\right)\)

\(\Leftrightarrow30x+9=36+24+32x\)

\(\Leftrightarrow30x+9=32x+60\)

\(\Leftrightarrow30x-32x=60-9\)

\(\Leftrightarrow-2x=51\)

\(\Leftrightarrow x=-\frac{51}{2}\)

3. \(\frac{8x-3}{4}-\frac{3x-2}{2}=\frac{2x-1}{2}+\frac{x+3}{4}\)

\(\Leftrightarrow8x-3-2\left(3x-2\right)=2\left(2x-1\right)+x+3\)

\(\Leftrightarrow8x-3-6x+4=4x-2+x+3\)

\(\Leftrightarrow2x+1=5x+1\)

\(\Leftrightarrow2x=5x\)

\(\Leftrightarrow x=0\)

19 tháng 8 2020

4) \(\frac{3\left(3-x\right)}{8}+\frac{2\left(5-x\right)}{3}=\frac{1-x}{2}-2\)

=> \(\frac{9-3x}{8}+\frac{10-2x}{3}=\frac{1-x}{2}-\frac{2}{1}\)

=> \(\frac{3\left(9-3x\right)}{24}+\frac{8\left(10-2x\right)}{24}=\frac{12\left(1-x\right)}{24}-\frac{48}{24}\)

=> \(\frac{27-9x}{24}+\frac{80-16x}{24}=\frac{12-12x}{24}-\frac{48}{24}\)

=> \(\frac{27-9x+80-16x}{24}=\frac{12-12x-48}{24}\)

=> 27 - 9x + 80 - 16x = 12 - 12x - 48

=> 27 - 9x + 80 - 16x - 12 + 12x + 48 = 0

=> (27 + 80 - 12 + 48) + (-9x - 16x + 12x) = 0

=> 143 - 13x = 0

=> 13x = 143

=> x = 11

5) \(\frac{2\left(x-3\right)}{7}+\frac{x-5}{3}-\frac{13x+4}{21}=0\)

=> \(\frac{2x-6}{7}+\frac{x-5}{3}-\frac{13x+4}{21}=0\)

=> \(\frac{3\left(2x-6\right)}{21}+\frac{7\left(x-5\right)}{21}-\frac{13x+4}{21}=0\)

=> \(\frac{6x-18}{21}+\frac{7x-35}{21}-\frac{13x+4}{21}=0\)

=> \(\frac{6x-18+7x-35-13x-4}{21}=0\)

=> 6x - 18 + 7x - 35 - 13x - 4 = 0

=> (6x + 7x - 13x) + (-18 - 35 - 4) = 0

=> -57 = 0(vô nghiệm)

6) \(\frac{6x+5}{2}-\left(2x+\frac{2x+1}{2}\right)=\frac{10x+3}{4}\)

=> \(\frac{6x+5}{2}-\frac{10x+3}{4}=2x+\frac{2x+1}{2}\)

=> \(\frac{2\left(6x+5\right)}{4}-\frac{10x+3}{4}=\frac{8x}{4}+\frac{2\left(2x+1\right)}{4}\)

=> \(\frac{12x+10}{4}-\frac{10x+3}{4}=\frac{8x}{4}+\frac{4x+2}{4}\)

=> \(\frac{12x+10-\left(10x+3\right)}{4}=\frac{8x+4x+2}{4}\)

=> \(\frac{12x+10-10x-3}{4}=\frac{12x+2}{4}\)

=> \(12x+10-10x-3=12x+2\)

=> \(2x+10-3=12x+2\)

=> 2x + 10 - 3 - 12x - 2 = 0

=> (2x - 12x) + (10 - 3 - 2) = 0

=> -10x + 5 = 0

=> -10x = -5

=> x = 1/2

7) \(\frac{2x-1}{5}-\frac{x-2}{3}-\frac{x+7}{15}=0\)

=> \(\frac{3\left(2x-1\right)}{15}-\frac{5\left(x-2\right)}{15}-\frac{x+7}{15}=0\)

=> \(\frac{6x-3}{15}-\frac{5x-10}{15}-\frac{x+7}{15}=0\)

=> \(\frac{6x-3-\left(5x-10\right)-\left(x+7\right)}{15}=0\)

=> 6x - 3 - 5x + 10 - x - 7 = 0

=> (6x - 5x - x) + (-3 + 10 - 7) = 0

=> 0x + 0 = 0

=> 0x = 0

=> x tùy ý

Bài 8 tự làm nhé

27 tháng 8 2018

\(5x-\frac{3-2x}{2}>\frac{7x-5}{2}+x\)

\(\Leftrightarrow\) \(\frac{10x}{2}-\frac{3-2x}{2}>\frac{7x-5}{2}+\frac{2x}{2}\)

\(\Rightarrow\) \(10x-3+2x>7x-5+2x\)

\(\Leftrightarrow\) \(10x+2x-7x-2x>-5+3\)

\(\Leftrightarrow\) \(3x>-2\) 

\(\Leftrightarrow\) \(x>-\frac{2}{3}\)

Vậy ................

27 tháng 8 2018

4x > (5x -2)/2

4x - 5x/2 > -1

3x/2 > -1

3x > -2

x>-2/3

22 tháng 1 2022

\(a,4x-6< 7x-12\)

\(\Leftrightarrow6< 3x\Leftrightarrow x>2\)

\(b,\frac{3x-7}{4}\ge2-\frac{x+5}{3}\)

\(\Leftrightarrow3\left(3x-7\right)\ge24-4\left(x+5\right)\)

\(\Leftrightarrow13x\ge25\Leftrightarrow x\ge\frac{25}{13}\)

\(c,\frac{3x-8}{-7}\ge1-\frac{x+2}{-3}\)

\(\Leftrightarrow-3\left(3x-8\right)\ge21+7\left(x+2\right)\)

\(\Leftrightarrow-16x\ge11\)

\(\Leftrightarrow x\le-\frac{11}{16}\)

\(d,-12-8x>3+2x-\left(5-7x\right)\)

\(\Leftrightarrow14>17x\Leftrightarrow x< \frac{14}{17}\)

\(e,-1+\frac{x-1}{-3}\le\frac{x+2}{-9}\)

\(\Leftrightarrow-9-3\left(x-1\right)\le-\left(x+2\right)\)

\(\Leftrightarrow-2x\le4\Leftrightarrow x\ge-2\)

\(d,\frac{10x+3}{8}=\frac{7-8x}{12}\)

\(\left(10x+3\right):8=\left(7-8x\right):12\)

\(\left(10x+3\right).\frac{1}{8}=\left(7-8x\right).\frac{1}{12}\)

\(\frac{5}{4}x+\frac{3}{8}=\frac{7}{12}-\frac{8}{12}x\)

\(\frac{5}{4}x+\frac{8}{12}x=\frac{7}{12}-\frac{3}{8}\)

\(\frac{23}{12}x=\frac{5}{24}\)

\(x=\frac{5}{46}\)

6 tháng 3 2020

E mới lớp 6 nên giải sai thì thông cảm ạ UwU

\(b,\frac{x}{10}-\left(\frac{x}{30}+\frac{2x}{45}\right)=\frac{4}{5}\)

\(< =>\frac{9x}{90}-\frac{7x}{90}=\frac{4}{5}\)

\(< =>\frac{x}{45}=\frac{32}{45}\)

\(< =>x=32\)

\(d,\frac{10x+3}{8}=\frac{7-8x}{12}\)

\(< =>\left(10x+3\right).12=\left(7-8x\right).8\)

\(< =>120x+36=56-64x\)

\(< =>184x=56-36=20\)

\(< =>x=\frac{20}{184}=\frac{5}{46}\)