\(\frac{1}{2}-x\left(x-1\right)=-x^2\)\(\Leftrightarrow\frac{1}{2}-x^2+x=-x^2\)\(\Leftrightarrow-x^2+x+x^2=-\frac{1}{2}\)\(\Leftrightarrow x=-\frac{1}{2}\)Câu trả lời: \(\frac{1}{2}-x\left(x-1\right)=-x^2\)\(\Leftrightarrow\frac{1}{2}-x^2+x=-x^2\)\(\Leftrightarrow-x^2+x+x^2=-\frac{1}{2}\)\(\Leftrightarrow x=-\frac{1}{2}\)