编写一个类,该类创建的对象可以计算等差数列的和

Question

编写一个类,该类创建的对象可以计算等差数列的和编写一个类,该类创建的对象可以计算等差数列的和

Answer 1

public class Slum {
public static void main(String[] args) {
//1,3,3
//等差数列：1,2,3... 前3项求和如下：
System.out.println("Sn = "+a1suman(1,3,3));
System.out.println("Sn = "+sumnda(3,1,1));
System.out.println("Sn = "+sumnda2(1,3,1));
}
//知道a1,an
public static int a1suman(int a1, int an, int n){
return (a1+an)*n/2;
}
//知道n,d,a1
public static int sumnda(int n, int a1, int d){
return n*a1+n*(n-1)*d/2;
}
//知道n,d,a1
public static int sumnda2(int a1, int n, int d){
return (2*a1+(n-1)*d)*n/2;
}
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