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27 tháng 9 2021

Ta có: \(\left\{{}\begin{matrix}x^2+2y+1=0\\y^2+2z+1=0\\z^2+2x+1=0\end{matrix}\right.\)

\(\Rightarrow x^2+2y+1+y^2+2z+1+z^2+2x+1=0\)

\(\Rightarrow\left(x+1\right)^2+\left(y+1\right)^2+\left(z+1\right)^2=0\)

\(\Rightarrow x=y=z=-1\)(do \(\left(x+1\right)^2,\left(y+1\right)^2,\left(z+1\right)^2\ge0\forall x,y,z\))

a) \(A=x^{2020}+y^{2020}+z^{2020}=\left(-1\right)^{2020}+\left(-1\right)^{2020}+\left(-1\right)^{2020}=1+1+1=3\)

b) \(B=\dfrac{1}{x^{2020}}+\dfrac{1}{y^{2020}}+\dfrac{1}{z^{2020}}=\dfrac{1}{\left(-1\right)^{2020}}+\dfrac{1}{\left(-1\right)^{2020}}+\dfrac{1}{\left(-1\right)^{2020}}=\dfrac{1}{1}+\dfrac{1}{1}+\dfrac{1}{1}=3\)

24 tháng 8 2023

\(M=x^{2023}-2023.\left(x^{2022}-x^{2021}+x^{2020}-x^{2019}+...+x^2-x\right)\)

Ta có : \(x=2022\Rightarrow x+1=2023\)

\(\Rightarrow M=x^{2023}-\left(x+1\right).\left(x^{2022}-x^{2021}+x^{2020}-x^{2019}+...+x^2-x\right)\)

\(\Rightarrow M=x^{2023}-\left(x+1\right)x^{2022}+\left(x+1\right)x^{2021}-\left(x+1\right)x^{2020}+\left(x+1\right)x^{2019}+...-\left(x+1\right)x^2+\left(x+1\right)x\)

\(\Rightarrow M=x^{2023}-x^{2023}-x^{2022}+x^{2022}+x^{2021}-x^{2021}-x^{2020}+x^{2020}+x^{2019}-x^{2019}-...-x^3-x^2+x^2+x\)

\(\Rightarrow M=x\)

\(\Rightarrow M=2022\)

Vậy \(M=2022\left(tạix=2022\right)\)

AH
Akai Haruma
Giáo viên
7 tháng 10 2023

Lời giải:
Với $x=3, y=\frac{1}{3}$ thì $xy=3.\frac{1}{3}=1$
Khi đó:

$A=xy+(xy)^2+(xy)^4+...+(xy)^{2022}=1+1^2+1^4+...+1^{2022}$

$=\underbrace{1+1+....+1}_{1012}=1012.1=1012$
b. Đề thiếu dữ kiện về $x,y$

24 tháng 7 2019

hehe chiều mình cũng thế

24 tháng 7 2019

https://diendantoanhoc.net/topic/74052-cho-xyz0-xyz1-tim-gtnn-c%E1%BB%A7a-p-fracx2yzyzfracy2zxzxfracz2xyxy/

vào là có ok

5 tháng 7 2016

\(x+y+z+8=2\sqrt{x-1}+4\sqrt{y-2}+6\sqrt{z-3}\) (ĐKXĐ : \(x\ge1;y\ge2;z\ge3\))

\(\Leftrightarrow\left(x-1-2\sqrt{x-1}+1\right)+\left(y-2-4\sqrt{y-2}+4\right)+\left(z-3-6\sqrt{z-3}+9\right)=0\)

\(\Leftrightarrow\left(\sqrt{x-1}-1\right)^2+\left(\sqrt{y-2}-2\right)^2+\left(\sqrt{z-3}-3\right)^2=0\)

Vì \(\left(\sqrt{x-1}-1\right)^2\ge0;\left(\sqrt{y-2}-2\right)^2\ge0;\left(\sqrt{z-3}-3\right)^2\ge0\)

nên phương trình tương đương với : \(\hept{\begin{cases}\left(\sqrt{x-1}-1\right)^2=0\\\left(\sqrt{y-2}-2\right)^2=0\\\left(\sqrt{z-3}-3\right)^2=0\end{cases}\Leftrightarrow\hept{\begin{cases}x=2\\y=6\\z=12\end{cases}}}\)(TMĐK)

Vậy nghiệm của phương trình :  \(\left(x;y;z\right)=\left(2;6;12\right)\)

4 tháng 10 2018

ez game

a) Ta có | x | >= 0 ; |x+1| >= 0 ; |x+2| >= 0 ; |x+3| >= 0

=> |x| + |x+1| + |x+2| + |x+3| >= 0

=> 6x >= 0

=> x >=0 ( đpcm )

b) Từ điều kiện x >= ( ở câu a )

=> x + x + 1 + x + 2 + x + 3 = 6x

=> 4x + 6 = 6x

=> 6 = 6x - 4x

=> 6 = 2x

=> x = 3

Vậy x = 3

4 tháng 10 2018

tk à

13 tháng 4 2020

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18 tháng 4 2020

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