\(0,\left(4\right)=\dfrac{4}{9}\)

I like playing football with my friends in the evening. At the weekend, I like playing chess with my sister.

a² + 2ab + b² = (a + b)²

4x² + 4xy + y² = (2x)² + 2.2x.y + y² = (2x + y)²

25x² + 10xy + y² = (5x)² + 2.5x.y + y² = (5x + y)²

Có: \(\left|2022-2x+y\right|\ge0\forall x,y\)

       \(\left(x-y-2021\right)^2\ge0\forall x,y\)

\(\Rightarrow\left|2022-2x+y\right|+\left(x-y-2021\right)^2\ge0\forall x,y\)

Mặt khác: \(\left|2022-2x+y\right|+\left(x-y-2021\right)^2=0\)

nên \(\left\{{}\begin{matrix}2022-2x+y=0\\x-y-2021=0\end{matrix}\right.\)           \(\Rightarrow\left\{{}\begin{matrix}-2x+y=-2022\\x-y=2021\end{matrix}\right.\)

\(\Rightarrow-2x+y+x-y=-2022+2021\)

\(\Rightarrow-x=-1\Leftrightarrow x=1\)

Khi đó: \(1-y=2021\) \(\Leftrightarrow y=-2020\)

\(\Rightarrow x+y=1-2020=-2019\)

\(\dfrac{5}{7}\times\dfrac{3}{4}=\dfrac{15}{28}\)

Vậy \(\dfrac{5}{7}\) của \(\dfrac{3}{4}\) là \(\dfrac{15}{28}\)

1 - a

2 - d

3 - c

4 - a

5 - c

6 - b

7 - a

8 - b

9 - b

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4. smell

5. taste