Ta có:

$\dfrac{x^4}{2x^2+1}+\dfrac{2x^2+1}{x^4}=2$

Điều kiện: $x\ne0$.

Đặt $t=\dfrac{x^4}{2x^2+1}>0$.

Khi đó:

$t+\dfrac{1}{t}=2$

$t^2-2t+1=0$

$(t-1)^2=0$

$t=1$

$\dfrac{x^4}{2x^2+1}=1$

$x^4=2x^2+1$

$x^4-2x^2-1=0$

Đặt $y=x^2\ge0$:

$y^2-2y-1=0$

$y=1+\sqrt2$ (do $y\ge0$)

$x^2=1+\sqrt2$

$x=\pm\sqrt{1+\sqrt2}$

Vậy $x=\pm\sqrt{1+\sqrt2}$.

Ta có:

$\left(\dfrac{x}{x-1}\right)^2+\left(\dfrac{x}{x+1}\right)^2=\dfrac{10}{9}$

Điều kiện: $x\ne\pm1$.

Quy đồng:

$\dfrac{x^2(x+1)^2+x^2(x-1)^2}{(x^2-1)^2}=\dfrac{10}{9}$

$\dfrac{x^2[(x+1)^2+(x-1)^2]}{(x^2-1)^2}=\dfrac{10}{9}$

$\dfrac{2x^2(x^2+1)}{(x^2-1)^2}=\dfrac{10}{9}$

$18x^2(x^2+1)=10(x^2-1)^2$

$9x^2(x^2+1)=5(x^2-1)^2$

$9x^4+9x^2=5x^4-10x^2+5$

$4x^4+19x^2-5=0$

Đặt $t=x^2\ge0$:

$4t^2+19t-5=0$

$(4t-1)(t+5)=0$

$t=\dfrac14$ (do $t\ge0$)

$x^2=\dfrac14$

$x=\pm\dfrac12$

Vậy $x=\pm\dfrac12$.

Ta có:

$x^3+3x^2-10x-24=0$

Nhóm các hạng tử:

$x^2(x+3)-10(x+3)=0$

$(x+3)(x^2-10)=0$

$x+3=0$ hoặc $x^2-10=0$

$x=-3$ hoặc $x=\pm\sqrt{10}$

Vậy $x\in{-3,-\sqrt{10},\sqrt{10}}$.

a: \(\Leftrightarrow x+2-3xm-m=5\)

\(\Leftrightarrow x\left(1-3m\right)=5+m-2=m+3\)

Để đây là pt bậc nhất thì -3m+1<>0

hay m<>1/3

b: Khi m=-1 thì pt sẽ là \(x\left(1+3\right)=-1+3=2\)

=>x=1/2

Ta có:

$\dfrac{6}{x^2-1}+5=\dfrac{8x-1}{4x+4}-\dfrac{12x-1}{4-4x}$

Điều kiện: $x\ne-1,\ x\ne1$.

Ta có:

$\dfrac{6}{(x-1)(x+1)}+5=\dfrac{8x-1}{4(x+1)}+\dfrac{12x-1}{4(x-1)}$

Quy đồng:

$\dfrac{6+5(x^2-1)}{x^2-1}=\dfrac{(8x-1)(x-1)+(12x-1)(x+1)}{4(x^2-1)}$

$\dfrac{5x^2+1}{x^2-1}=\dfrac{20x^2+2x-2}{4(x^2-1)}$

$4(5x^2+1)=20x^2+2x-2$

$20x^2+4=20x^2+2x-2$

$2x=6$

$x=3$

Vậy $x=3$.

Ta có:

$\dfrac{2x+1}{2x-1}-\dfrac{2x-1}{2x+1}=\dfrac{8}{4x^2-1}$

Điều kiện: $x\ne\pm\dfrac12$.

Quy đồng:

$\dfrac{(2x+1)^2-(2x-1)^2}{4x^2-1}=\dfrac{8}{4x^2-1}$

$\dfrac{8x}{4x^2-1}=\dfrac{8}{4x^2-1}$

$8x=8$

$x=1$

Vậy $x=1$.

a) \(3x-5\le x+1\)

\(\Leftrightarrow3x-x\le1+5\)

\(\Leftrightarrow2x\le6\)

\(\Leftrightarrow x\le3\)

Vậy.............

b) \(\frac{2x-2}{2}>\frac{2-x+2}{3}\)

\(\Leftrightarrow3\left(2x-2\right)>2\left(2-x+2\right)\)

\(\Leftrightarrow6x-6>4-2x+4\)

\(\Leftrightarrow6x+2x>4+4+6\)

\(\Leftrightarrow8x>14\)

\(\Leftrightarrow x>\frac{7}{4}\)

Vậy..................

a,\(3x-5\le x+1\Leftrightarrow2x\le6\Leftrightarrow x\le3\)

b,\(\frac{2x-2}{3}>2-\frac{x+2}{2}\)

\(\Leftrightarrow2\left(2x-2\right)>12-3\left(x+2\right)\)

\(\Leftrightarrow4x-4>12-3x-6\)

\(\Leftrightarrow7x>10\Leftrightarrow x>\frac{10}{7}\)

Câu 1 : D

Câu 2 : A

Câu 3 : B

Câu 4 : A

Câu 5 : C

lớp 8 thì mấy bài này dễ thôi

Giải pt :

\(\left(x+2\right)\left(3x+1\right)+x^2=4\)

\(\Leftrightarrow\left(x+2\right)\left(3x+1\right)+x^2-4=0\)

\(\Leftrightarrow\left(x+2\right)\left(3x+1\right)+\left(x^2-4\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left(3x+1\right)+\left(x+2\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left[\left(3x+1\right)+\left(x-2\right)\right]=0\)

\(\Leftrightarrow\left(x+2\right)\left(3x+1+x-2\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left(4x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+2=0\\4x-1=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\4x=1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=\dfrac{1}{4}\end{matrix}\right.\)

Tập nghiệm của pt là : \(S=\left\{-2;\dfrac{1}{4}\right\}\)

cam on

a) 3x + 18 = 0

<=>  3*(x+6)=0

<=> x+6=0

<=> x=-6

Vậy S={-6}

6x-7=3x+2

<=> 6x - 3x= 2+7

<=> 3x=9

<=> x=3 

Vậy S={ 3}

c) mk ko hỉu rõ đề