bn lấy (2718+1564) x 134

Bn Nguyễn Phạm Lan Chi / Bn trả lời rõ ra cho mình đc ko?                  

\(=27.\left(-53\right)+27.\left(-47\right)\\ =27.\left[\left(-53\right)+\left(-47\right)\right]\\ =27.-100\\ =-2700\)

-2700

27.(-53)+(-27).47

=27.(−53)+27.(−47)

=27.[(−53)+(−47)]

=27.−100

=−2700

b: \(BC\cdot\sin B\cdot\sin C\)

\(=BC\cdot\dfrac{AC}{BC}\cdot\dfrac{AB}{BC}\)

\(=\dfrac{BC\cdot AH\cdot BC}{BC^2}=AH\)

Ta có: \(\left|y+3\right|\ge0\forall y\)

\(\left|2x+y\right|\ge0\forall x,y\)

Do đó: \(\left|y+3\right|+\left|2x+y\right|\ge0\forall x,y\)

Dấu '=' xảy ra khi \(\left\{{}\begin{matrix}y+3=0\\2x+y=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}y=-3\\2x-3=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3}{2}\\y=-3\end{matrix}\right.\)