题目

         Not many years ago, a wealthy and rather strange old man named Johnson lived alone in a village in the south of England. He had made a lot of money in trading with foreign countries. When he was seventy – five, he gave $ 60,000 to the village school to buy land and equipment for a children’s ground. As a result of his kindness, he became famous. Many people came to visit him. Among them was a newspaperman. During their talk, Johnson remarked that he was seventy-five and expected to live to be hundred. The newspaperman asked him how he managed to be healthy at seventy3．若m=2n2+n+1，则8n2-4m+4n-3的值等于-7．