Question

bài 1,2 là như nào vậy mn.

 

Answer 1

Bài 2: 

a: \(A=\left(x-y\right)^2+\left(y-1\right)^2-3\ge-3\forall x,y\)

Dấu '=' xảy ra khi x=y=1

b: \(B=-\left(2x-5\right)^2+2\le2\forall x\)

Dấu '=' xảy ra khi \(x=\dfrac{5}{2}\)

Answer 2

\(1,\\ a,\Rightarrow3^{3x}=3^6:9\\ \Rightarrow3^{3x}=3^6:3^2=3^4\\ \Rightarrow3x=4\Rightarrow x=\dfrac{4}{3}\\ b,\Rightarrow3^{2x-1}=27^{x+2}=3^{3\left(x+2\right)}\\ \Rightarrow2x-1=3x+6\\ \Rightarrow x=-7\\ 2,\\ a,A=\left(x-y\right)^2+\left(y-1\right)^2-3\ge-3\\ A_{min}=-3\Leftrightarrow\left\{{}\begin{matrix}x-y=0\\y-1=0\end{matrix}\right.\Leftrightarrow x=y=1\\ b,B=-\left(2x-5\right)^2+2\le2\\ B_{max}=2\Leftrightarrow2x-5=0\Leftrightarrow x=\dfrac{5}{2}\)