Question

giải pt sau \(2x^2-\sqrt{2}x-2=0\)

Answer 1

chỗ \(S=\left\{\sqrt{2};\frac{-\sqrt{2}}{2}\right\}\)  nha bạn mình sai chỗ đó

Answer 2

\(\Delta=b^2-4ac=\left(-\sqrt{2}\right)^2-4.2.\left(-2\right)=18\)

\(\Delta>0\Rightarrow\)pt có 2 nghiệm phân biệt \(\sqrt{\Delta}=\sqrt{18}=3\sqrt{2}\)

\(x_1=\frac{-b+\sqrt{\Delta}}{2a}=\frac{\sqrt{2}+3\sqrt{2}}{2.2}=\sqrt{2}\)

\(x_2=\frac{-b-\sqrt{\Delta}}{2a}=\frac{\sqrt{2}-3\sqrt{2}}{2.2}=\frac{-\sqrt{2}}{2}\)

Vậy \(S=\left\{2;\frac{-\sqrt{2}}{2}\right\}\)