hiu hiu

help me !!!!

ko biết ok

a, \(x-\frac{5x+2}{6}=\frac{7-3x}{4}\)

\(\frac{12x}{12}-\frac{2\left(5x+2\right)}{12}=\frac{3\left(7-3x\right)}{12}\)

\(12x-10x-4=21-9x\)

\(11x=25\)

\(x=\frac{24}{11}\)

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

\(\frac{10x+3}{12}=\frac{15+8x}{9}\)

\(9\left(10x+3\right)=12\left(15+8x\right)\)

\(3\left(10x+3\right)=4\left(8x+15\right)\)

\(30x+9=32x+60\)

\(-2x=51\)

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

\(c,\frac{x}{3}-\frac{2x+1}{2}=\frac{x}{6}-x\)

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

\(2x-6x-3=x-6x\)

\(x=3\)

P/s: Bn xem lại đề bài phần d nha!

=.= hk tốt!!

câu d sao bn đề đúng r ạ

tức là đề có 2 dấu = hả bn?

a)       

\(\begin{array}{l}\,\,\,\,\,\,\,\frac{{5x - 2}}{3} = \frac{{5 - 3x}}{2}\\\frac{{2\left( {5x - 2} \right)}}{6} = \frac{{3\left( {5 - 3x} \right)}}{6}\\\,2\left( {5x - 2} \right) = 3\left( {5 - 3x} \right)\\\,\,\,\,\,\,10x - 4 = 15 - 9x\\\,\,\,10x + 9x = 15 + 4\\\,\,\,\,\,\,\,\,\,\,\,\,\,19x = 19\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 19:19\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 1.\end{array}\)

Vậy phương trình có nghiệm \(x = 1\).

b)      

\(\begin{array}{l}\,\,\,\,\,\,\frac{{10x + 3}}{{12}} = 1 + \frac{{6 + 8x}}{9}\\\frac{{3\left( {10x + 3} \right)}}{{36}} = \frac{{36}}{{36}} + \frac{{4\left( {6 + 8x} \right)}}{{36}}\\\,3\left( {10x + 3} \right) = 36 + 4\left( {6 + 8x} \right)\\\,\,\,\,\,\,\,30x + 9 = 36 + 24 + 32x\\\,\,\,\,\,\,\,30x + 9 = 60 + 32x\\\,30x - 32x = 60 - 9\\\,\,\,\,\,\,\,\,\,\,\,\,\, - 2x = 51\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x =  - \frac{{51}}{2}.\end{array}\)

Vậy phương trình có nghiệm \(x =  - \frac{{51}}{2}\).

c)       

\(\begin{array}{l}\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{{7x - 1}}{6} + 2x = \frac{{16 - x}}{5}\\\frac{{5\left( {7x - 1} \right)}}{{30}} + \frac{{30.2x}}{{30}} = \frac{{6\left( {16 - x} \right)}}{{30}}\\\,\,5\left( {7x - 1} \right) + 30.2x = 6\left( {16 - x} \right)\\\,\,\,\,\,\,\,\,\,\,35x - 5 + 60x = 96 - 6x\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,95x - 5 = 96 - 6x\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,95x + 6x = 96 + 5\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,101x = 101\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 101:101\\\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,x = 1\end{array}\)

Vậy phương trình có nghiệm \(x = 1\).

`b,2(x+1)=5x-7`

`=>2x+2=5x-7`

`=>3x=9`

`=>x=3`

`c,3-4x(25-2x)=8x^2+x-300`

`<=>3-100x+8x^2=8x^2+x-300`

`<=>101x=303`

`<=>x=3`

`d,(10x+3)/12=1+(6+8x)/9`

`<=>(10x+3)/12=(8x+15)/9`

`<=>30x+9=32x+60`

`<=>2x=-51`

`<=>x=-51/2`

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

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

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

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

\(\Leftrightarrow2x=5x\)

\(\Leftrightarrow x=0\)

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