# Java Program to Compute a3-b3 where Value of a and b are Given

In the previous article we have discussed Java Program to Compute a3+b3 where Value of a and b are Given

In this program we are going to see how to compute a3-b3   where value of a and b are given by using Java programming language.

## Java Program to Compute a3-b3 where Value of a and b are Given

The formula of a3-b3 is given below.

a3-b3  = (a – b)3 + 3ab(a – b) = a3 – b3 – 3a2b + 3ab2+ 3a2b – 3ab2

Now we will convert this into a valid Java expression.

Let x= a3-b3

=  (a – b)3 + 3ab(a – b)

= a3 – b3 – 3a2b + 3ab2+ 3a2b – 3ab2

=(a*a*a)-(b*b*b)-(3*a*a*b)+(3*a*b*b)+( 3*a*a*b)-(3*a*b*b)

Example:

Suppose a=4 and b=2

Then
a3+b3
=(a*a*a)-(b*b*b)-(3*a*a*b)+(3*a*b*b)+( 3*a*a*b)-(3*a*b*b)
=(4*4*4)-(2*2*2)-(3*4*4*2)+(3*4*2*2)+ (3*4*4*2)-(3*4*2*2)
=56

Now let’s see different ways to compute a3-b3

### Method-1: Java Program to Compute a3-b3 where Value of a and b are Given By Using Static Input Value

Approach:

• Declare and initialize two integer variables say a and b.
• By using the formula compute a3-b3  .
• Print the result.

Program:

class Main
{
public static void main(String[] args)
{
//declare the first integer variable with an integer value
int a= 4;
System.out.println("a= " +a);
//declare the second integer variable with an integer value
int b= 2;
System.out.println("b= "+b);
//declare another integer variable and assigned the formulated value to it.
int c=(a*a*a)-(b*b*b)-(3*a*a*b)+(3*a*b*b)+( 3*a*a*b)-(3*a*b*b);
System.out.println("a3 - b3= "+c);
}
}

Output:

a= 4
b= 2
a3 - b3= 56

### Method-2: Java Program to Compute a3-b3 where Value of a and b are Given By Using User Input Value

Approach:

• Declare two integer variables say a and b.
• Take the value of a and b as user input by using Scanner class.
• Then by using the formula compute a3-b3  .
• Print the result.

Program:

import java.util.Scanner;
class Main
{
public static void main(String[] args)
{
//create object of scanner class.
Scanner sc=new Scanner(System.in);
System.out.print("a= ");
//Take the first input from the user.
int a= sc.nextInt();
System.out.print("b= ");
//Take the second input from the user.
int b= sc.nextInt();
//declare another integer variable and assigned the formulated value to it.
int c=(a*a*a)-(b*b*b)-(3*a*a*b)+(3*a*b*b)+( 3*a*a*b)-(3*a*b*b);
System.out.println("a3 - b3= "+c);
}
}

Output:

a= 4
b= 5
a3 - b3= -61

### Method-3: Java Program to Compute a3-b3 where Value of a and b are Given By Using User Defined Method

Approach:

• Declare two integer variables say a and b.
• Take the value of a and b as user input by using Scanner class.
• Then call a user defined method say computeValue() and pass a and b as parameter.
• Then inside method by using the formula compute a3-b3  .
• Print the result.

Program:

import java.util.Scanner;
class Main
{
public static void main(String[] args)
{
//create object of scanner class.
Scanner sc=new Scanner(System.in);
System.out.print("a= ");
//Take the first input from the user.
int a= sc.nextInt();
System.out.print("b= ");
//Take the second input from the user.
int b= sc.nextInt();
//call the function
computeValue(a,b);
}
//define the method
public static void computeValue(int a, int b)
{
//declare another integer variable and assigned the formulated value to it.
int c=(a*a*a)-(b*b*b)-(3*a*a*b)+(3*a*b*b)+( 3*a*a*b)-(3*a*b*b);
System.out.println("a3 - b3= "+c);
}
}

Output:

a= 8
b= 10
a3 - b3= -488

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