试问把一个西瓜切五刀,最后可切出多少块来? 问题1 一个平面用n条直线去划分,划分出的部分数最多是多少? 当n=1时,平面被划分为2块,a1=2．当n=2时,增加的直线与原来的一条直线有一交点,此交点把增加的直线一分为二,每一部分通过所分平面中的一块,且把这块一分为二,所以平面比n=1时增加2块,a2=a1+2． How many pieces of fruit can be cut out by cutting a piece of watermelon? Question 1 What is the maximum number of parts of a plane divided by n straight lines? When n=1, the plane is divided into two pieces, a1 =2. When n=2, the added straight line has an intersection with the original straight line. This intersecting point divides the added straight line into two parts. Each part passes through one of the divided planes, and divides this piece into two, so the plane ratio is When n=1, add 2 blocks, a2=a1+2.