\(\dfrac{x-1}{2023}+\dfrac{x-2}{2022}=\dfrac{x-3}{2021}+\dfrac{x-4}{2020}\)

`<=>(x-1)/2023-1+(x-2)/2022-1=(x-3)/2021-1+(x-4)/2020-1`

`<=>(x-2024)/2023+(x-2024)/2022=(x-2024)/2021+(x-2024)/2020`

`<=>(x-2024)(1/2023+1/2022-1/2021-1/2020)=0`

`<=>x-2024=0(1/2023+1/2022-1/2021-1/2020>0)`

`<=>x=2024`

=>\(\left(\dfrac{x-1}{2023}-1\right)+\left(\dfrac{x-2}{2022}-1\right)=\left(\dfrac{x-3}{2021}-1\right)+\left(\dfrac{x-4}{2020}-1\right)\)

=>x-2024=0

=>x=2024

\(\dfrac{x-1}{2023}+\dfrac{x-2}{2022}=\dfrac{x-3}{2021}+\dfrac{x-4}{2020}\)

⇔\(\dfrac{x-1}{2023}-1+\dfrac{x-2}{2022}-1=\dfrac{x-3}{2021}-1+\dfrac{x-4}{2020}\)

⇔\(\dfrac{x-1}{2023}-\dfrac{2023}{2023}+\dfrac{x-2}{2022}-\dfrac{2022}{2022}=\dfrac{x-3}{2021}-\dfrac{2021}{2021}+\dfrac{x-4}{2020}-\dfrac{2020}{2020}\)

⇔\(\dfrac{x-2024}{2023}+\dfrac{x-2024}{2022}=\dfrac{x-2024}{2021}+\dfrac{x-2024}{2020}\)

⇔\(\dfrac{x-2024}{2023}+\dfrac{x-2024}{2022}-\dfrac{x-2024}{2021}-\dfrac{x-2024}{2020}=0\)

⇔\(\left(x-2024\right)\left(\dfrac{1}{2023}+\dfrac{1}{2022}-\dfrac{1}{2021}-\dfrac{1}{2020}\ne0\right)\)

⇔\(x-2024=0\)

⇔\(x=2024\)

PT (1) \(\Leftrightarrow2\left(x^2+y^2+z^2\right)-2\left(xy+yz+xz\right)=0\)

\(\Leftrightarrow\left(x^2-2xy+y^2\right)+\left(y^2-2yz+z^2\right)+\left(z^2-2zx+x^2\right)=0\)

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

Nhận thấy VT\(\ge\)0 với mọi x,y,z

Dấu = xảy ra <=> x=y=z

Thay x=y=z vào pt (2) ta được:

\(3x^{2021}=3^{2022}\) \(\Leftrightarrow x^{2021}=3^{2021}\) \(\Leftrightarrow x=3\)

\(\Rightarrow x=y=z=3\)

Vậy (x;y;z)=(3;3;3)

Ta có \(x+1=2022\)

\(P\left(x\right)=x^{101}-\left(x+1\right)x^{100}+...+\left(x+1\right)x-1\)

\(=x^{101}-x^{101}-x^{100}+...+x^2+x-1=x-1\)

-> P(x) = 2020 

 \(=\dfrac{2021}{2022}\left(\dfrac{6}{17}-\dfrac{23}{17}\right)+\dfrac{2021}{2022}=\dfrac{-2021}{2022}+\dfrac{2021}{2022}=0\)

hhelp