Question

Câu 2

Answer 1

Câu 2:

\(a,\Leftrightarrow x=1;y=3\Leftrightarrow3=2+m-1\Leftrightarrow m=2\\ \text{Khi đó }y=2x+1\\ b,\text{PT hoành độ giao điểm: }2x+m-1=x-1\\ \Leftrightarrow m=-x\\ \text{Mà }x=0\Leftrightarrow m=0\)

Câu 4:

\(A=x+y+\dfrac{1}{2x}+\dfrac{2}{y}=\left(\dfrac{x}{2}+\dfrac{1}{2x}\right)+\left(\dfrac{y}{2}+\dfrac{2}{y}\right)+\dfrac{1}{2}\left(x+y\right)\\ A\ge2\sqrt{\dfrac{x}{2}\cdot\dfrac{1}{2x}}+2\sqrt{\dfrac{y}{2}\cdot\dfrac{2}{y}}+\dfrac{1}{2}\cdot3=1+2+\dfrac{3}{2}=\dfrac{9}{2}\\ A_{min}=\dfrac{9}{2}\Leftrightarrow\left(x;y\right)=\left(1;2\right)\)