a) 7x - 35 = 0

<=> 7x = 0 + 35

<=> 7x = 35

<=> x = 5

b) 4x - x - 18 = 0

<=> 3x - 18 = 0

<=> 3x = 0 + 18

<=> 3x = 18

<=> x = 5

c) x - 6 = 8 - x

<=> x - 6 + x = 8

<=> 2x - 6 = 8

<=> 2x = 8 + 6

<=> 2x = 14

<=> x = 7

d) 48 - 5x = 39 - 2x

<=> 48 - 5x + 2x = 39

<=> 48 - 3x = 39

<=> -3x = 39 - 48

<=> -3x = -9

<=> x = 3

có bị viết nhầm thì thông cảm nha!

la`thu'hai nga`y 19 nhe

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

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

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

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

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

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

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

\(\Leftrightarrow-16x\ge11\)

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

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

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

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

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

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

\(\frac{5x-3}{6}-\frac{7x-1}{4}-\frac{4x+2}{7}+5=0\)

<=> \(\frac{14\left(5x-3\right)-21\left(7x-1\right)-12\left(4x+2\right)+420}{84}=0\)

<=> 70x - 42 - 147x + 21 - 48x -24 + 420 = 0

<=> -125x + 375 = 0

<=> -125x = -375

<=> x = 3

Vậy S = {3}

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

<=> \(\frac{15\left(2x+1\right)-100-2\left(3x+2\right)}{20}=\frac{8\left(3x-1\right)}{20}\)

<=> 30x + 15 - 100 - 6x - 4 = 24x - 8

<=> 24x - 24x = -8 + 89

<=> 0x = 81

=> pt vô nghiệm

\(\frac{3x^2-7x+5}{x^2-x-x}-x+\frac{1}{x+1}< 0\Leftrightarrow\frac{x^2-6x+11}{\left(x-2\right)\left(x+1\right)}< 0\Leftrightarrow\frac{\left(x-3\right)^2+2}{\left(x-2\right)\left(x+1\right)}< 0\)

=> (x-2)(x+1)<0 ( vì (x-3)^2+2>0 lđ)

lại có x+1>x-2 => x-2<0 và x+1>0

=> -1<x<2

học tốt

Cho mình làm lại nha:

\(\frac{3x^2-7x+5}{\left(x+1\right)\left(x-2\right)}< \frac{2x+2-1}{x+1}.\)

\(\Leftrightarrow\frac{3x^2-7x+5}{\left(x+1\right)\left(x-2\right)}-\frac{2x+1}{x+1}< 0.\)

\(\Leftrightarrow\frac{3x^2-7x+5-\left(2x+1\right)\left(x-2\right)}{\left(x+1\right)\left(x-2\right)}< 0.\)

\(\Leftrightarrow\frac{3x^2-7x+5-2x^2+4x-x+2}{\left(x+1\right)\left(x-2\right)}< 0.\)

\(\Leftrightarrow\frac{x^2-4x+4+3}{\left(x+1\right)\left(x-2\right)}< 0.\)

\(\Leftrightarrow\frac{\left(x-2\right)^2+3}{\left(x+1\right)\left(x-2\right)}< 0\Leftrightarrow\left(x+1\right)\left(x-2\right)< 0.\)

ta có x+1>x-2 => x+1>0;x-2<0 => -1<x<2

đọc lộn xíu xin lỗi nha

học tốt

a , 2x -3 = 5x + 6

    2x -5x=6+3

    -3x = 9

     x =9 :(-3)

   x= -3

a) 2x-5x=3+6

-3x=9

x=-3

vậy........

b)(2x+1).(3x-2)-(5x-8).(2x+1)=0

(2x+1).(3x-2-2x-1)=0

(2x-1).(x-3)=0

==>x=1/2 ; x=3

c)(2x+1).5-(7x+5)=(2x-2).3

10x+5-7x-5=6x-6

3x=6x-6

3x-6x=6

-3x=6

x=-2

a) 2x - 3 = 5x + 6

<=> -3x = 9

<=> x = -3

b) (2x + 1).(3x - 2) = (5x - 8).(2x + 1)

<=> 6x² - 4x + 3x - 2 = 10x² + 5x - 16x -8

<=> -4x² - 10x + 6 = 0

<=> \(\orbr{\begin{cases}x=\frac{1}{2}\\x=-3\end{cases}}\)

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

<=> \(\frac{5.\left(2\text{x}+1\right)}{5.3}-\frac{7\text{x}+5}{15}=\frac{3.\left(2\text{x}-2\right)}{3.5}\)

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

<=> -3x + 16 = 0

<=> -3x = -16

<=> x = \(\frac{16}{3}\)

d) \(\frac{3x}{x-2}-\frac{x}{x-5}=\frac{3\text{x}}{\left(x-2\right).\left(5-x\right)}\)

<=> \(\frac{3\text{x}\left(x-5\right)-x\left(x-2\right)}{\left(x-2\right).\left(5-x\right)}=\frac{3\text{x}}{\left(x-2\right).\left(5-x\right)}\)

<=> 3x² - 15x - x² + 2x - 3x = 0

*Câu e dễ quá, bạn tự làm nhé :v*