一个长方体的地面积是21,另外,其中一个面的面积是30.请问体积是多少?答案是220.1,The area of the base of the rectangular box is 21 and the area of one of the faces is 30.Each of the dimensions j,k,and l is an integer greater than 1.What is the volume of the rectangular box?（答案是220）If n>1 and each of the three integers n,n+2,n+4 is a prime number,then the set of three such numbers is claaed a"prime triple"There are how many different prime triples?（答案是1）
问题描述：
一个长方体的地面积是21,另外,其中一个面的面积是30.
请问体积是多少?答案是220.
1,The area of the base of the rectangular box is 21 and the area of one of the faces is 30.Each of the dimensions j,k,and l is an integer greater than 1.What is the volume of the rectangular box?（答案是220）
If n>1 and each of the three integers n,n+2,n+4 is a prime number,then the set of three such numbers is claaed a"prime triple"There are how many different prime triples?（答案是1）
答
用原英语写出来吧
答
1.明显是210,因为21和30只有公因数3,因为每条边整数所以一条边是3,所以长宽高为10,3,7,v=210
2.明显只有一组3,5,7,因为n,n+2,n+4中一定会有一个是3的倍数,而只有3是质数,所以只有1组.