Algebra formulas solve using java

import java.io.*;
class Formulas
{
public static void main(String args[])throws IOException
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.println("1.(a+b)(a-b)=(a^2-b^2)");
System.out.println("2.(a+b)^2=(a^2+b^2+2ab)");
System.out.println("3.(a-b)^2=(a^2+b^2-2ab)");
System.out.println("4.(a^3+b^3)=(a+b) (a^2-ab+b^2)");
System.out.println("5.(a+b+c)^2=a^2+b^2+c^2+2(ab+bc+ca)");
System.out.println("6.(a^3-b^3)=(a-b) (a^2+ab+b^2)");
System.out.println("7. (a^3+b^3+c^3-3abc)=(a+b+c)(a^2+b^2+c^2-ab-bc-ac)");
System.out.println("choose your formulas");
int ch=Integer.parseInt(br.readLine());
switch(ch)
{
case 1:
System.out.println("Enter the a value");
double a=Double.parseDouble(br.readLine());
System.out.println("Enter the b value");
double b=Double.parseDouble(br.readLine());
double c=Math.pow(a,2);
System.out.println(a);
double d=Math.pow(b,2);
System.out.println(b);
double fans=c-d;
System.out.println("the formula value is"+fans);
break;
case 2:
System.out.println("your formula is (a+b)^2=(a^2+b^2+2ab) ");
System.out.println("Enter the a value:");
a=Double.parseDouble(br.readLine());
System.out.println("Enter the b value:");
b=Double.parseDouble(br.readLine());
c=Math.pow(a,2);
d=Math.pow(b,2);
double e=2*a*b;
double fin=c+d+e;
System.out.println("The answer is"+fin);
break;
case 3:
System.out.println("your formula using (a+b)^2=(a^2+b^2-2ab)");
System.out.println("Enter the a value");
a=Double.parseDouble(br.readLine());
System.out.println("Enter the b value");
b=Double.parseDouble(br.readLine());
c=Math.pow(a,2);
d=Math.pow(b,2);
e=2*a*b;
fin=c+d-e;
System.out.println("the final answer is"+fin);
break;
case 4:
System.out.println("choosing formula is (a^3+b^3)= (a+b) (a^2-ab+b^2)");
System.out.println("Enter the a value:");
a=Double.parseDouble(br.readLine());
System.out.println("Enter the b value:");
b=Double.parseDouble(br.readLine());
c=a+b;
d=Math.pow(a,2);
e=Math.pow(b,2);
double f=a*b;
double g=d-f;
double h=g+e;
fin=c*h;
System.out.println("The answer is"+fin);
break;
case 5:
System.out.println("Your selecting formula is (a+b+c)^2=a^2+b^2+c^2+2(ab+bc+ca)");
System.out.println("Enter the a value");
a=Double.parseDouble(br.readLine());
System.out.println("Enter the b value");
b=Double.parseDouble(br.readLine());
System.out.println("Enter the c value");
c=Double.parseDouble(br.readLine());
d=Math.pow(a,2);
e=Math.pow(b,2);
f=Math.pow(c,2);
g=a*b;
h=b*c;
double i=c*a;
double j=g+h+i;
double k=2*j;
System.out.println(k);
double l=d+e+f;
fin=k+l;
System.out.println("The answer is"+fin);
break;
case 6:
System.out.println("you are choosing (a-b) (a^2+ab+b^2)");
System.out.println("Enter the a value");
a=Double.parseDouble(br.readLine());
System.out.println("Enter the b value");
b=Double.parseDouble(br.readLine());
c=a-b;
d=Math.pow(a,2);
e=Math.pow(b,2);
f=a*b;
g=d+e+f;
h=c*g;
System.out.println("the answer value is"+h);
break;
case 7:
System.out.println("Your choosing formula is (a+b+c)(a^2+b^2+c^2-ab-bc-ac)");
System.out.println("Enter the a value");
a=Double.parseDouble(br.readLine());
System.out.println("Enter the b value");
b=Double.parseDouble(br.readLine());
System.out.println("Enter the c value");
c=Double.parseDouble(br.readLine());
d=a+b+c;
e=Math.pow(a,2);
f=Math.pow(b,2);
g=Math.pow(c,2);
h=a*b;
i=b*c;
j=a*c;
k=e+f+g;
l=h-i-j;
double m=k-l;
double n=d*m;
System.out.println("The answer is"+n);
break;
}
}
}