Có gì sao sót thì thôi nha .

Ta có : 3.( x -3)²  + 2x = x . ( x + 1 ) + 9

<=> 3.x² -16.x + 27       = x. ( x + 1 ) + 9

<=> 3.x² - 16.x + 27       = x² + x+ 9

<=> 3.x² - 16.x +27 - x² -x - 9 = 0

<=>2.x² -17.x +18 = 0

<=> x=\(\frac{17\pm\sqrt{\left(-17\right)^2-144}}{4}\)

<=> x= \(\frac{17\pm\sqrt{145}}{4}\)

<=> x = \(\frac{17-\sqrt{145}}{4};\frac{17+\sqrt{145}}{4}\)

a, \(2+\frac{3}{x-5}=1\Leftrightarrow\frac{3}{x-5}=-1\)

\(\Leftrightarrow x-5=\frac{3}{-1}=-3\Leftrightarrow x=2\)

Vậy .............

b, ....................

\(\Leftrightarrow\frac{x-9}{x^2-3^2}-\frac{2}{x+3}=\frac{1}{x-3}\)

\(\Leftrightarrow\frac{x-9}{\left(x-3\right)\left(x+3\right)}-\frac{2x-6}{\left(x-3\right)\left(x+3\right)}-\frac{x+3}{\left(x-3\right)\left(x+3\right)}=0\)

\(\Leftrightarrow\frac{x-9-2x+6-x+3}{\left(x-3\right)\left(x+3\right)}=0\)

\(\Leftrightarrow\frac{-2x}{\left(x-3\right)\left(x+3\right)}=0\Rightarrow-2x=0\Rightarrow x=0\)

Vậy .............

Bài 1:

a) (3x - 2)(4x + 5) = 0

<=> 3x - 2 = 0 hoặc 4x + 5 = 0

<=> 3x = 2 hoặc 4x = -5

<=> x = 2/3 hoặc x = -5/4

b) (2,3x - 6,9)(0,1x + 2) = 0

<=> 2,3x - 6,9 = 0 hoặc 0,1x + 2 = 0

<=> 2,3x = 6,9 hoặc 0,1x = -2

<=> x = 3 hoặc x = -20

c) (4x + 2)(x^2 + 1) = 0

<=> 4x + 2 = 0 hoặc x^2 + 1 # 0

<=> 4x = -2

<=> x = -2/4 = -1/2

d) (2x + 7)(x - 5)(5x + 1) = 0

<=> 2x + 7 = 0 hoặc x - 5 = 0 hoặc 5x + 1 = 0

<=> 2x = -7 hoặc x = 5 hoặc 5x = -1

<=> x = -7/2 hoặc x = 5 hoặc x = -1/5

bài 2:

a, (3x+2)(x^2-1)=(9x^2-4)(x+1)

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

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

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

b, x(x+3)(x-3)-(x-2)(x^2-2x+4)=0

x(x^2-9)-(x^3+8)=0

x^3-9x-x^3-8=0

-9x-8=0

tự tìm x nha