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

a, y x 8 = y + 10

=> 8y=y+10

=> 8y-y=10

=> 7y=10

=> y=10/7

b, y x 10 + 9 = y x 3 + 3

=> 10y+9=3y+3

=>10y+9-3y=3

=> 10y-3y+9=3

=> 10y-3y=3-9

=> 7y=-6

=> y=-6/7

:)

y= 6/7 nhaaaaaaa!

2020-y:8×10=1000

y:8×10=2020-1000

y:8×10=1020

y:8=1020:10

y:8=102

y=102×8

y=816

Vậy y=816

y = 816

tk cho mk nha !! Chúc bạn năm mới vui vẻ gặp nhiều may mắn

Thank you very much

y=816

\(\left(2x-10\right)^2+\left(8-y\right)^{10}-10=-10\)

\(\Rightarrow\left(2x-10\right)^2+\left(8-y\right)^{10}=0\)

Vì \(\hept{\begin{cases}\left(2x-10\right)^2\ge0\\\left(8-y\right)^{10}\ge0\end{cases}\Rightarrow\left(2x-10\right)^2+\left(8-y\right)^{10}\ge0}\)

Mà \(\left(2x-10\right)^2+\left(8-y\right)^{10}=0\)

\(\Rightarrow\hept{\begin{cases}\left(2x-10\right)^2=0\\\left(8-y\right)^{10}=0\end{cases}\Rightarrow\hept{\begin{cases}2x-10=0\\8-y=0\end{cases}\Rightarrow}\hept{\begin{cases}x=5\\y=8\end{cases}}}\)

\(\left(2x-10\right)^2+\left(8-y\right)^{10}-10=-10\)

\(\Leftrightarrow\left(2x-10\right)^2+\left(8-y\right)^{10}=0\)

Mà \(\hept{\begin{cases}\left(2x-10\right)^2\ge0\\\left(8-y\right)^{10}\ge0\end{cases}}\)

\(\Leftrightarrow\hept{\begin{cases}\left(2x-10\right)^2=0\\\left(8-y\right)^{10}=0\end{cases}}\)

\(\Leftrightarrow\hept{\begin{cases}2x-10=0\\8-y=0\end{cases}}\) \(\Leftrightarrow\hept{\begin{cases}x=5\\y=8\end{cases}}\)

Vậy ..

Tìm y  biết:

2020 - y : 8 x 10 = 1000

          y : 8 x 10 = 2000 - 1000

          y : 8 x 10 = 1000

          y : 8        = 1000 : 10

          y : 8        = 100

          y             = 100 x 8

          y             = 800

Vậy y = 800

\(2020-y:8\times10=1000\)

        \(2020-y:80=1000\)

                        \(y:80=2020-1000\)

                        \(y:80=1020\)

                              \(y=1020\times80\)

                              \(y=81600\)

2020-y:8=1000:10

2020-y:8=100

2020-y=100x8

2020-y=800

y=2020-800=1220