Question

Mình cần gấp bài này (PP: phương pháp)

Answer 1

\(a,\Leftrightarrow\left(x^2+4x+4\right)+\left(4y^2-4y+1\right)+5=0\\ \Leftrightarrow\left(x+2\right)^2+\left(2y-1\right)^2+5=0\)

Mà \(\left(x+2\right)^2+\left(2y-1\right)^2+5\ge5>0\)

Vậy pt vô nghiệm

\(b,\Leftrightarrow\left(x^2-2xy+y^2\right)+\left(2x^2+10x+\dfrac{25}{2}\right)+\dfrac{33}{2}=0\\ \Leftrightarrow\left(x-y\right)^2+2\left(x^2+\dfrac{5}{2}x+\dfrac{25}{4}\right)+\dfrac{33}{2}=0\\ \Leftrightarrow\left(x-y\right)^2+2\left(x+\dfrac{5}{2}\right)^2+\dfrac{33}{2}=0\)

Mà \(\left(x-y\right)^2+2\left(x+\dfrac{5}{2}\right)^2+\dfrac{33}{2}\ge\dfrac{33}{2}>0\)

Vậy pt vô nghiệm