我正在编写一个程序，它从等式中获取 a、b 和 c，并使用它们使用以下公式找到 x： http ://www.purplemath.com/modules/quads/qform01.gif 。
我遇到的问题是，当我插入方程 1x^2 +3x +4 时，我得到 x = -Infinity 和 x = infinity 而不是 x = 1 和 x = -4。
这是我的代码：
第一类：
public class quadratictest
{
public static void main(String args[])
{
DecimalFormat df = new DecimalFormat("#.###");
System.out.println("--------------------------------------------------");
System.out.println(" ~Quadratic Formula~");
System.out.println("--------------------------------------------------");
System.out.println("in a polynomial, there are 3 important numbers used");
System.out.println("to figure out x. they are a, b, and c, shown below.\n");
System.out.println("\t\t1x^2 +3x +4");
System.out.println("\t\t^ ^ ^");
System.out.println("\t\ta b c");
Scanner input = new Scanner(System.in);
System.out.print("\nPlease type a, b, and c here[a b c]: ");
int a = input.nextInt();
int b = input.nextInt();
int c = input.nextInt();
mathey quad = new quadsong(a,b,c);
System.out.println("------------");
System.out.println(quad.solveb());
System.out.println(quad.solvea());
//System.out.println("x =" +df.format(quad.solvea()));
//System.out.println("x =" +df.format(quad.solveb()));
System.out.println("------------");
}
}
第 2 类：
import java.util.*;
import java.io.*;
import java.text.DecimalFormat;
/**
* Write a description of class quadsong here.
*
* @author (your name)
* @version (a version number or a date)
*/
public class mathey
{
int a;int b;int c;
double solution1;
double solution2;
public mathey(int aN, int bN, int cN)
{
int a = aN;
int b = bN;
int c = cN;
solvea();
solveb();
}
public double solvea()
{
solution1 = ( (b*-1) + Math.sqrt((b^2)-(4*a*c)))/(a+a);
if (solution1 == Math.floor(solution1))
{
return solution1;
}
else
{
return 0;
}
}
public double solveb()
{
solution2 = ( (b*-1) - Math.sqrt((b^2)-(4*a*c)))/(2*a);
if (solution2 == Math.floor(solution2))
{
return solution2;
}
else
{
return 0;
}
}
}
这是我的输出：
--------------------------------------------------
~Quadratic Formula~
--------------------------------------------------
in a polynomial, there are 3 important numbers used
to figure out x. they are a, b, and c, shown below.
1x^2 +3x +4
^ ^ ^
a b c
Please type a, b, and c here[a b c]: 1 3 4
------------
x =Infinity
x =-Infinity
------------
怎么了？提前致谢！PS对不起代码格式，idk为什么它不能像我想要的那样工作哈哈