x:54+x:16=217

x:(54+16)=217

x:70=217

x   =217*70

x   =15190

x:[16=54] =217

x ; 70 =217

x =217 nhân 70 = 15190

x = 15190

9.(2x-20)+2x=-580

=>18x-180+2x=-580

=>18x+2x=(-580)+180

=>20x=-400

=>x=(-400):20

=>x=-20

9.(2x-20)+2x = -580

18x-180+2x=-580

18x+2x-180=-580

20x-180=-580

20x=-580+180

20x=-400

x=-400:20

x=-20

Vậy x=-20

9.(2x-20)+2x=-580

=>18x-180+2x=-580

=>18x+2x=(-580)+180

=>20x=-400

=>x=(-400):20

=>x=-20

9.(2x-20)+2x = -580

18x-180+2x=-580

18x+2x-180=-580

20x-180=-580

20x=-580+180

20x=-400

x=-400:20

x=-20

Vậy x=-20

Trước tiên bạn nhân 9.(2x-20) 

<=>18x-180-2x=-580

Sau đó bạn thu gọn biểu thức

<=>20x-180=-580

Đến Dây chuyển vế ròi tính biểu thức

<=>20x=-580+180    

<=>20x=-400

=>x=-20

Vậy X=-20

Chọn (k) đúng cho mình nha :) :)

1/2.x+3/5.(x-2)=3

1/2.x+3/5.x-3/5.2=3

(1/2+3/5).x-6/5=15/5

(5/10+6/10).x=15/5+6/5

11/10.x =21/5

         x = 21/5:11/10

         x = 21/5.10/11

         x= 42/11

vậy x=42/11

1/2 . x + 3/5 . ( x - 2 ) = 3 

1/2 . x + 3/5 . x - 3/5 . 2 = 3

( 1/2 + 3/5 ) . x - 6/5 = 15/5

( 5/10 + 6/10 ) . x = 15/5 + 6/5

11/10 . x = 21/5

           x = 21/5 : 11/10

           x = 21/5 . 10/11

          x = 42 / 11

Vậy x = 42/11

Đúng nha Chích Cute

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

\(\frac{1}{2}x+\frac{3}{5}x-\frac{3}{5}\cdot2=3\)

\(\left(\frac{1}{2}+\frac{3}{5}\right)x-\frac{6}{5}=3\)

\(\frac{11}{10}x-\frac{6}{5}=3\)

\(\frac{11}{10}x=3+\frac{6}{5}\)

\(\frac{11}{10}x=\frac{21}{5}\)

\(x=\frac{21}{5}:\frac{11}{10}\)

\(x=\frac{42}{11}\)

Lời giải:

1. 
$x^3+3x^2-16x-48=(x^3+3x^2)-(16x+48)=x^2(x+3)-16(x+3)$

$=(x+3)(x^2-16)=(x+3)(x-4)(x+4)$

2.

$4x(x-3y)+12y(3y-x)=4x(x-3y)-12y(x-3y)=(x-3y)(4x-12y)=4(x-3y)(x-3y)=4(x-3y)^2$

3.

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

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

`2x-2/3=1/2`

`2x=1/2+2/3`

`2x=7/6`

`x=7/6:2=7/12`

\(2x-\dfrac{2}{3}=\dfrac{1}{2}\Leftrightarrow2x=\dfrac{2}{3}+\dfrac{1}{2}=\dfrac{7}{6}\Leftrightarrow x=\dfrac{7}{6}:2=\dfrac{7}{12}\)

2x - 2/3 = 1/2

2x = 1/2 + 2/3 = 7/6

x = 7/6 : 2 = 7/12

vậy x = 7/12

b) \(M=\frac{x^2+1}{x-1}=\frac{x^2-1}{x-1}+\frac{2}{x-1}=\frac{\left(x-1\right)\left(x+1\right)}{x-1}+\frac{2}{x-1}=x+1+\frac{2}{x-1}\)

Áp dụng bđt Cô si cho 2 số dương ta được: \(x-1+\frac{2}{x-1}\ge2\sqrt{\left(x-1\right).\frac{2}{x-1}}=2\sqrt{2}\)

=>\(M=x+1+\frac{2}{x-1}\ge2\sqrt{2}+2\)

Dấu  "=" xảy ra khi \(x=\sqrt{2}+1\)

c) \(N=\left(x-1\right)\left(x+5\right)\left(x^2+4x+5\right)=\left(x^2+4x-5\right)\left(x^2+4x+5\right)=\left(x^2+4x\right)^2-25\)

\(\left(x^2+4x\right)^2\ge0\Rightarrow\left(x^2+4x\right)^2-25\ge-25\)

Dấu "=" xảy ra khi (x²+4x)²=0 <=> x²+4x=0 <=> x(x+4)=0 <=> x=0 hoặc x=-4

\(5x\left(x-3\right)^2-5\left(x-1\right)^3+15\left(x+2\right)\left(x-2\right)=5\)

\(\Leftrightarrow5x\left(x^2-6x+9\right)-5\left(x^3-3x^2+3x-1\right)+15\left(x^2-4\right)=5\)

\(\Leftrightarrow5x^3-30x^2+45x-5x^3+15x^2-15x+5+15x^2-60=5\)

\(\Leftrightarrow30x=60\)

\(\Leftrightarrow x=2\)

\(x^2+4x+y^2-2xy+x^2+4=0\)

\(\Leftrightarrow\left(x^2-2xy+y^2\right)+\left(x^2+4x+4\right)=0\)

\(\Leftrightarrow\left(x-y\right)^2+\left(x+2\right)^2=0\)

vì \(\left(x-y\right)^2\ge0;\left(x+2\right)^2\ge0\)nên

\(\Rightarrow\orbr{\begin{cases}x+2=0\\x-y=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-2\\y=-2\end{cases}\Rightarrow}x=y=-2}\)

1)

\((x+2)(x+3)(x+4)(x+5)-24\\=[(x+2)(x+5)]\cdot[(x+3)(x+4)]-24\\=(x^2+7x+10)(x^2+7x+12)-24\)

Đặt \(x^2+7x+10=y\), khi đó biểu thức trở thành:

\(y(y+2)-24\\=y^2+2y-24\\=y^2+2y+1-25\\=(y+1)^2-5^2\\=(y+1-5)(y+1+5)\\=(y-4)(y+6)\\=(x^2+7x+10-4)(x^2+7x+10+6)\\=(x^2+7x+6)(x^2+7x+16)\)

2) Bạn xem lại đề!