Question

если x^2+z^2+x+z+1/2=0 , чему равно xz=?

Answer 1

$(x^2+2x\cdot\frac{1}{2}+\frac{1}{4})+(z^2+2z\cdot\frac{1}{2}+\frac{1}{4})=0;$

$(x+\frac{1}{2})^2+(z+\frac{1}{2})^2=0\Leftrightarrow \left \{ {{x+1/2=0} \atop {z+1/2=0}} \right. \Leftrightarrow \left \{ {{x=-1/2} \atop {z=-1/2}} \right. \Rightarrow xz=\frac{1}{4}$

Ответ: $\frac{1}{4}$