Cho mik hỏi:
Tìm X bik: 3 - ( 2 x X + 1/2 ) : 1/2 = 2
Giúp mik với :'')))
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\(\text{K - 2016 = }\frac{\text{1 + ( 1 + 2 ) + ( 1 + 2 + 3 ) + ... + ( 1 + 2 + 3 + ... + 2017 )}}{\text{2017 x 1 + 2016 x 2 + 2015 x 3 + ... + 2 x 2016 + 1 x 2017}}\)
Ta có : 1 . 1 = 1 ; (-1 ) . (-1) = 1
TH1 : 1 . 1 = 1
=> x + 2 = 1 => x = 1
y - 1 = 1 => y = 2
TH2 : ( - 1) . (-1) = 1
=> x + 2 = -1 => x = -3
y - 1 = -1 => y = 0
Vậy để (x+2) . (y-1) = 1 thì x = -1 ; y =2
hoặc x = -3 ; y =0
kick mik nhé
1=1.1=(-1).(-1).Nên ta có bảng sau
x+2 | x | y-1 | y |
1 | -1 | 1 | 2 |
-1 | -3 | -1 | 0 |
Vậy x=-1 thì y=2
x=-3 thì y=0
x+2 là ước cảu x+ 7
\(\Rightarrow x+7⋮x+2\)
\(\Rightarrow x+2+5⋮x+2\)
mà \(x+2⋮x+2\)
\(\Rightarrow x+2\inƯ\left(5\right)=\left\{\pm1;\pm5\right\}\)
\(\Rightarrow x\in\left\{-1;\pm3;-7\right\}\)
a) Có \(\left|x-3y\right|^5\ge0\);\(\left|y+4\right|\ge0\)
\(\rightarrow\left|x-3y\right|^5+\left|y+4\right|\ge0\)
mà \(\left|x-3y\right|^5+\left|y+4\right|=0\)
\(\rightarrow\left\{{}\begin{matrix}\left|x-3y\right|^5=0\\\left|y+4\right|=0\end{matrix}\right.\)
\(\rightarrow\left\{{}\begin{matrix}x=3y\\y=-4\end{matrix}\right.\)
\(\rightarrow\left\{{}\begin{matrix}x=-12\\y=-4\end{matrix}\right.\)
b) Tương tự câu a, ta có:
\(\left\{{}\begin{matrix}\left|x-y-5\right|=0\\\left(y-3\right)^4=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=y+5\\y=3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=8\\y=3\end{matrix}\right.\)
c. Tương tự, ta có:
\(\left\{{}\begin{matrix}\left|x+3y-1\right|=0\\\left|y+2\right|=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=1-3y\\y=-2\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=7\\y=-2\end{matrix}\right.\)
a. \(\left|x-3y\right|^5\ge0,\left|y+4\right|\ge0\Rightarrow\left|x-3y\right|^5+\left|y+4\right|\ge0\) \(\Rightarrow VT\ge VP\)
Dấu bằng xảy ra \(\Leftrightarrow\left\{{}\begin{matrix}\left|x-3y\right|^5=0\\\left|y+4\right|=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=3y\\y=-4\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=-12\\y=-4\end{matrix}\right.\) Vậy...
b. \(\left|x-y-5\right|\ge0,\left(y-3\right)^4\ge0\Rightarrow\left|x-y-5\right|+\left(y-3\right)^4\ge0\) \(\Rightarrow VT\ge VP\)
Dấu bằng xảy ra \(\Leftrightarrow\left\{{}\begin{matrix}\left|x-y-5\right|=0\\\left(y-3\right)^4=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=y+5\\y=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=8\\y=3\end{matrix}\right.\) Vậy ...
c. \(\left|x+3y-1\right|\ge0,3\cdot\left|y+2\right|\ge0\Rightarrow\left|x+3y-1\right|+3\left|y+2\right|\ge0\) \(\Rightarrow VT\ge VP\) Dấu bằng xảy ra \(\Leftrightarrow\left\{{}\begin{matrix}\left|x+3y-1\right|=0\\3\left|y+2\right|=0\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=1-3y\\y=-2\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1-\left(-2\right)\cdot3=7\\y=-2\end{matrix}\right.\) Vậy...
a; \(x\) + 6 ⋮ \(x\) + 1 (\(x\) ≠ - 1)
\(x\) + 1 + 5 ⋮ \(x\) + 1
\(x\) + 1 \(\in\) Ư(5) = {-5; -1; 1; 5}
\(x\) \(\in\) {-6; -2; 0; 4}
\(x\) + 6 ⋮ \(x\) + (-1) (\(x\) ≠ 1)
\(x\) + - 1 + 7 ⋮ \(x\) - 1
7 ⋮ \(x\) - 1
\(x\) - 1 \(\in\) Ư(7) = {-7; -1; 1; 7}
\(x\) \(\in\) {-6; 0; 2; 8}
b; \(x\) + 6 ⋮ \(x\) - 2 (đk \(x\) ≠ 2)
\(x\) - 2 + 8 ⋮ \(x\) - 2
8 ⋮ \(x\) - 2
\(x\) - 2 \(\in\) Ư(8) = {-8; -4; -2; -1; 1; 2; 4; 8}
\(x\) \(\in\) {-6; -2; 0; 1; 3; 4; 10}
\(x\) + 6 ⋮ \(x\) + (-2)
\(x\) + 6 ⋮ \(x\) - 2
giống với ý trên
a: x/3-1/6=1/5
=>x/3=11/30
hay x=11/90
b: =>1/2x=2
hay x=4
c: =>2/3:x=-7-1/3=-22/3
=>x=-1/11
ÉT Ô ÉT
Câu 3: Tìm x biết:
|x + 1| + |x + 2| + |x + 2020| = 4x
Giúp mik với!!!
Mik hứa Tick cho… Pls
TH1 : \(x< -2020\)
<=> | x + 1 | + | x + 2 | + | x + 2020 | = - ( x + 1 ) - ( x + 2 ) - ( x + 2020 ) = 4x
<=> -3x - 2023 = 4x <=> -7x = 2023 <=> x = -289
TH2 : \(-2020\le x< -2\)
<=> | x + 1 | + | x + 2 | + | x + 2020 | = - ( x + 1 ) - ( x + 2 ) + x + 2020 = 4x
<=> -x + 2017 = 4x
<=> -5x = -2017 <=> x = 2017/5 ( = 403,4 )
TH3 : \(-2\le x< -1\)
<=> | x + 1 | + | x + 2 | + | x + 2020 | = - ( x + 1 ) + x + 2 + x + 2020 = 4x
<=> x + 2021 = 4x <=> -3x = -2021 <=> x = 2021/3
TH4 : \(x>-1\)
<=> | x + 1 | + | x + 2 | + | x + 2020 | = x + 1 + x + 2 + x + 2020 = 4x
<=> 3x + 2023 = 4x
<=> -x = -2023 <=> x = 2023
Vậy...
TH1: x ≥ 0
Khi đó \(\left|x+1\right|+\left|x+2\right|+\left|x+2020\right|=x+1+x+2+x+2020\)
\(=3x+2023=4x\)
Suy ra \(4x-3x=x=2023\) (thỏa mãn điều kiện)
TH2: x < 0
Khi đó 4x < 0 hay vế phải luôn là một số âm. Tuy nhiên vế trái luôn luôn có giá trị lớn hơn 0 nên luôn là 0 hoặc là một số dương, suy ra vô lí.
Tóm lại, x = 2023.
3 - (2 x \(x\) + \(\dfrac{1}{2}\)) : \(\dfrac{1}{2}\) = 2
(2 x \(x\) + \(\dfrac{1}{2}\)) : \(\dfrac{1}{2}\) = 3 - 2
(2 x \(x\) + \(\dfrac{1}{2}\)) : \(\dfrac{1}{2}\) = 1
2 x \(x\) + \(\dfrac{1}{2}\) = 1 x \(\dfrac{1}{2}\)
2 x \(x\) + \(\dfrac{1}{2}\) = \(\dfrac{1}{2}\)
2 x \(x\) = \(\dfrac{1}{2}\) - \(\dfrac{1}{2}\)
2 x \(x\) = 0
\(x\) = 0 : 2
\(x\) = 0
3 - ( 2 x X + 1/2 ) : 1/2 = 2
3 - ( 2 x X + 1/2 ) : 1/2 = 3 - 2
2 x X + 1/2 = 1 x 1/2
2 x X + 1/2 = 1/2
2 x X = 1/2 - 1/2
2 x X = 0
X = 0 : 2
X = 0