One night, a doctor was sleeping at home when his doorbell began to ring. When he opened the door he saw a man (16) outside.“Excuse me, Doctor,” said the man.“Can you come to a place
Peter is thirteen. He is 1 Grade Two this year. He likes to play football and watch football matches. And he often 2 newspapers. He does his best to know where and when a football match
可解得qn=2,
=－2.
(1－q4n)=(－2)×(1－24)=30.