\((x^{^{2}}+y^{^{2}}-4)+k(x-y-1)=0\)

\((x^{^{2}}+kx)+(y^{^{2}}-ky)=4+k\)
NAMO_EQN__ 160 1 (x^{^{2}}+kx)+(y^{^{2}}-ky)=4+k
\((x^{^{2}}+kx+\frac{k^{^{2}}}{4})+(y^{^{2}}-ky+\frac{k^{^{2}}}{4})=4+k+\frac{k^{^{2}}}{4}+\frac{k^{^{2}}}{4}\)
NAMO_EQN__ 160 1 (x^{^{2}}+kx+\frac{k^{^{2}}}{4})+(y^{^{2}}-ky+\frac{k^{^{2}}}{4})=4+k+\frac{k^{^{2}}}{4}+\frac{k^{^{2}}}{4}
\((x+\frac{k}{2})^{^{2}}+(y-\frac{k}{2})^{^{2}}=\frac{2k^{^{2}}+4k+16}{4}\)
NAMO_EQN__ 160 1 (x+\frac{k}{2})^{^{2}}+(y-\frac{k}{2})^{^{2}}=\frac{2k^{^{2}}+4k+16}{4}
\(2k^{^{2}}+4k+16=2(k^{^{2}}+2k+1)-2+16=2(k+1)^{^{2}}+14>0\)
NAMO_EQN__ 160 1 2k^{^{2}}+4k+16=2(k^{^{2}}+2k+1)-2+16=2(k+1)^{^{2}}+14>0
中心
\((-\frac{k}{2},\frac{k}{2})\)
NAMO_EQN__ 160 1 (-\frac{k}{2},\frac{k}{2})
、半径
\(\frac{\sqrt{2k^{^{2}}+4k+16}}{2}\)
NAMO_EQN__ 160 1 \frac{\sqrt{2k^{^{2}}+4k+16}}{2}
の円………（答）