题目

My newly-rented small apartment was far away from the centre of London and it was becoming essential for me to find a job, so finally I spent a whole morning getting to town and putting my name down to be considered by London Transport for a job on the underground. They were looking for guards, not drivers. This suited me. I couldn’t drive a car but thought that I could probably guard a train, and perhaps continue to write my poems between stations. The writers Keats and Chekhov had been doctors. T.S. Eliot had worked in a bank and Wallace Stevens for an insurance company. I’d be a subway 已知方程x2＋y2－2(m＋3)x＋2(1－4m2)y＋16m4＋9＝0表示一个圆．(1)求实数m的取值范围；(2)求该圆半径r的取值范围；(3)求圆心的轨迹方程．