设实数abc满足a^-bc-8a+7=0,b^+c^+bc-6a+6=0.求a的取植范围.

a²-bc-8a+7=0,b²+c²+bc-6a+6=0 相加 a²+b²+c²-14a+13=0 (a-7)²+b²+c²-36=0 (a-7)²=36-(b²+c²) b²+c²>=0 -(b²+c²)<=0 36-(b²+c²)<=36 所以0<=(a-7)²<=