`(3x+2)/3 <= (x-4)/7`

`<=>7(3x+2) <= 3(x-4)`

`<=>21x+14 <= 3x-12`

`<=> 18x <=-26`

`<=>x <= -13/9`

Vậy `x<=-13/9`.

\(\left(2x-5\right).2=\left(x+2\right).3\)

\(\Rightarrow4x-10=3x+6\)

\(\Rightarrow x=16\)

\(\dfrac{2x+5}{3}=\dfrac{x+2}{2}\)

MTC : 6

Quy đồng mẫu thức :

\(\Rightarrow\) \(\dfrac{2\left(2x+5\right)}{6}=\)\(\dfrac{3\left(x+2\right)}{6}\)

 Suy ra : 2(2x + 5) = 3(x + 2)

          \(\Leftrightarrow\) 4x + 10 = 3x + 6

          \(\Leftrightarrow\) 4x + 10 - 3x - 6 = 0

          \(\Leftrightarrow\) x + 4 = 0

          \(\Leftrightarrow\) x = - 4

       Vậy S = \(\left\{-4\right\}\)

 Chúc bạn học tốt

ĐK: ` x\ne \pm 3`

`(x+1)/(x-3)+(x-1)/(x+3)=(x+6)/(x^2-9)`

`<=>(x+1)(x+3)+(x-1)(x-3)=x+6`

`<=>x^2+4x+3+x^2-4x+3=x+6`

`<=>2x^2+6=x+6`

`<=>2x^2-x=0`

`<=>x(2x-1)=0`

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=\dfrac{1}{2}\end{matrix}\right.\)

Vậy `S={0; 1/2}`.

ĐKXĐ: x ≠ -3, x ≠ 3

\(\dfrac{x+1}{x-3}+\dfrac{x-1}{x+3}=\dfrac{x+6}{x^2-9}\)

\(\Leftrightarrow\dfrac{\left(x+1\right)\left(x+3\right)+\left(x-1\right)\left(x-3\right)}{\left(x-3\right)\left(x+3\right)}=\dfrac{x+6}{\left(x-3\right)\left(x+3\right)}\)

\(\Rightarrow x^2+4x+3+x^2-4x+3=x+6\)

\(\Leftrightarrow2x^2-x=0\)

\(\Leftrightarrow x\left(2x-1\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\left(tm\right)\\x=\dfrac{1}{2}\left(tm\right)\end{matrix}\right.\)

Vậy...

\(\dfrac{x+1}{x-3}+\dfrac{x-1}{x+3}=\dfrac{x+6}{x^2-9}\)(a)

ĐKXĐ\(\left\{{}\begin{matrix}x-3\ne0\\x+3\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne3\\x\ne-3\end{matrix}\right.\)

(a)\(\Leftrightarrow\dfrac{x+1}{x-3}+\dfrac{x-1}{x+3}=\dfrac{x+6}{\left(x-3\right)\left(x+3\right)}\)

\(\Leftrightarrow\left(x+1\right).\left(x+3\right)+\left(x-1\right).\left(x-3\right)=x+6\)

\(\Leftrightarrow x^2+3x+x+3+x^2-3x-x+3=x+6\)

\(\Leftrightarrow x^2+3x+x+x^2-3x-x-x=6-3-3\)

\(\Leftrightarrow2x^2-x=0\)

\(\Leftrightarrow x\left(2x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\2x-1=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\2x=1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\left(thỏa-mãn-ĐKXĐ\right)\\x=\dfrac{1}{2}\left(thỏa-mãn-ĐKXĐ\right)\end{matrix}\right.\)

Vậy S = \(\left\{0;\dfrac{1}{2}\right\}\)

\(\dfrac{3-3x}{5}=\dfrac{x-1}{2}\\ \Leftrightarrow2\left(3-3x\right)=5x-5\\ \Leftrightarrow6-6x=5x-5\\ \Leftrightarrow-6x+5x=-5-6\\ \Leftrightarrow-x=-11\\ \Rightarrow x=11\)

\(=6x^4y^4-x^3y^3+\dfrac{1}{2}x^4y^2\)

1.

\(-4\le\dfrac{x^2-2x-7}{x^2+1}\le1\)

\(\Leftrightarrow\left\{{}\begin{matrix}x^2-2x-7\le x^2+1\\-4x^2-4\le x^2-2x-7\end{matrix}\right.\) (Do \(x^2+1>0\))

\(\Leftrightarrow\left\{{}\begin{matrix}x\ge-4\\\left[{}\begin{matrix}x\ge1\\x\le-\dfrac{3}{5}\end{matrix}\right.\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x\ge1\\-4\le x\le-\dfrac{3}{5}\end{matrix}\right.\)

2.

\(\dfrac{1}{13}\le\dfrac{x^2-2x-2}{x^2-5x+7}\le1\)

\(\Leftrightarrow\left\{{}\begin{matrix}x^2-5x+7\le13x^2-26x-26\\x^2-2x-2\le x^2-5x+7\end{matrix}\right.\) (Do \(x^2-5x+7>0\))

\(\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}x\ge\dfrac{11}{4}\\x\le-1\end{matrix}\right.\\x\le3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}\dfrac{11}{4}\le x\le3\\x\le-1\end{matrix}\right.\)

x\(\le\)11

=>3(x-1)-2(x-2)<=6/4(x-3)

=>3x-3-2x+4<=3/2x-9/2

=>-1/2x<=-9/2-1=-11/2

=>x>=11