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NV
8 tháng 1

a.

\(10⋮\left(x-1\right)\)

\(\Rightarrow x-1=Ư\left(10\right)\)

\(\Rightarrow x-1=\left\{-10;-5;-2;-1;1;2;5;10\right\}\)

\(\Rightarrow x=\left\{-9;-4;-1;0;2;3;6;11\right\}\)

b.

\(\left(x+5\right)⋮\left(x-2\right)\Rightarrow\left(x-2\right)+7⋮x-2\)

\(\Rightarrow7⋮x-2\)

\(\Rightarrow x-2=Ư\left(7\right)=\left\{-7;-1;1;7\right\}\)

\(\Rightarrow x=\left\{-5;1;3;9\right\}\)

c.

\(\left(3x+8\right)⋮\left(x-1\right)\)

\(\Rightarrow\left(3x-3+11\right)⋮\left(x-1\right)\)

\(\Rightarrow3\left(x-1\right)+11⋮x-1\)

\(\Rightarrow11⋮\left(x-1\right)\)

\(\Rightarrow x-1=Ư\left(11\right)=\left\{-11;-1;1;11\right\}\)

\(\Rightarrow x=\left\{-10;0;2;12\right\}\)

21 tháng 1 2021

a, \(\left|4x-8\right|\le8\)

\(\Leftrightarrow\left(\left|4x-8\right|\right)^2\le64\)

\(\Leftrightarrow16x^2-64x+64\le64\)

\(\Leftrightarrow16x^2-64x\le0\)

\(\Leftrightarrow16x\left(x-4\right)\le0\)

\(\Leftrightarrow0\le x\le4\)

b, \(\left|x-5\right|\le4\)

\(\Leftrightarrow\left(\left|x-5\right|\right)^2\le16\)

\(\Leftrightarrow x^2-10x+25\le16\)

\(\Leftrightarrow x^2-10x+9\le0\)

\(\Leftrightarrow1\le x\le9\)

\(\Rightarrow x\in\left\{1;2;3;4;5;6;7;8;9\right\}\)

c, \(\left|2x+1\right|< 3x\)

TH1: \(x\ge-\dfrac{1}{2}\)

\(\left|2x+1\right|< 3x\)

\(\Leftrightarrow2x+1< 3x\)

\(\Leftrightarrow x>1\)

\(\Rightarrow\left\{{}\begin{matrix}x\in Z\\x\in\left(1;2018\right)\end{matrix}\right.\)

TH2: \(x< -\dfrac{1}{2}\)

\(\left|2x+1\right|< 3x\)

\(\Leftrightarrow-2x-1< 3x\)

\(\Leftrightarrow x>-\dfrac{1}{5}\left(l\right)\)

Vậy \(\left\{{}\begin{matrix}x\in Z\\x\in\left(1;2018\right)\end{matrix}\right.\)

21 tháng 1 2021

d, \(\left|x+1\right|+\left|x\right|< 3\)

\(\Leftrightarrow x+1+x+2\left|x^2+x\right|< 9\)

\(\Leftrightarrow\left|x^2+x\right|< 4-x\)

Xét hai trường hợp để phá dấu giá trị tuyệt đối

e, Tương tự câu d

a/ \(x=\dfrac{-5}{12}\)

b/ \(x\approx-1,9526\)

c/ \(x=\dfrac{21-i\sqrt{199}}{10}\)

d/ \(x=\dfrac{-20}{13}\)

25 tháng 7 2021

a) (x-2)3+6(x+1)2-x3+12=0

⇒ x3-6x2+12x-8+6(x2+2x+1)-x3+12=0

⇒ x3-6x2+12x-8+6x2+12x+6-x3+12=0

⇒ 24x+10=0

⇒ 24x=-10

⇒ x=-5/12

22 tháng 12 2020

Rảnh rỗi thật sự .-.

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11 tháng 1 2023

\(8,1-\left(x-6\right)=4\left(2-2x\right)\)

\(\Leftrightarrow1-x+6=8-8x\)

\(\Leftrightarrow-x+8x=8-1-6\)

\(\Leftrightarrow7x=1\)

\(\Leftrightarrow x=\dfrac{1}{7}\)

\(9,\left(3x-2\right)\left(x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}3x-2=0\\x+5=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{2}{3}\\x=-5\end{matrix}\right.\)

\(10,\left(x+3\right)\left(x^2+2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x^2+2=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=\varnothing\end{matrix}\right.\)

 

11 tháng 1 2023

`8)1-(x-5)=4(2-2x)`

`<=>1-x+5=8-6x`

`<=>5x=2<=>x=2/5`

`9)(3x-2)(x+5)=0`

`<=>[(x=2/3),(x=-5):}`

`10)(x+3)(x^2+2)=0`

  Mà `x^2+2 > 0 AA x`

 `=>x+3=0`

`<=>x=-3`

`11)(5x-1)(x^2-9)=0`

`<=>(5x-1)(x-3)(x+3)=0`

`<=>[(x=1/5),(x=3),(x=-3):}`

`12)x(x-3)+3(x-3)=0`

`<=>(x-3)(x+3)=0`

`<=>[(x=3),(x=-3):}`

`13)x(x-5)-4x+20=0`

`<=>x(x-5)-4(x-5)=0`

`<=>(x-5)(x-4)=0`

`<=>[(x=5),(x=4):}`

`14)x^2+4x-5=0`

`<=>x^2+5x-x-5=0`

`<=>(x+5)(x-1)=0`

`<=>[(x=-5),(x=1):}`

12 tháng 10 2023

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8 tháng 9 2023

Bạn xem lại đề nhé.

a) \(A=x^2+5y^2+2xy-4x-8y+2015\)

 

\(A=x^2-4x+4-2y\left(x-2\right)+y^2+2011+4y^2\)

\(A=\left(x-2\right)^2-2y\left(x-2\right)+y^2+2011+4y^2\)

\(A=\left(x-2-y\right)^2+4y^2+2011\)

Vì \(\left(x-y-2\right)^2\ge0;4y^2\ge0\)

\(\Rightarrow A_{min}=2011\)

Dấu bằng xảy ra : \(\Leftrightarrow\left\{{}\begin{matrix}x-y-2=0\\4y^2=0\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}x=2\\y=0\end{matrix}\right.\)