Form the Cubic equation from the given roots
Given the roots of a cubic equation A, B and C, the task is to form the Cubic equation from the given roots.
Note: The given roots are integral.
Examples:
Input: A = 1, B = 2, C = 3
Output: x^3 – 6x^2 + 11x – 6 = 0
Explanation:
Since 1, 2, and 3 are roots of the cubic equations, Then equation is given by:
(x – 1)(x – 2)(x – 3) = 0
(x – 1)(x^2 – 5x + 6) = 0
x^3 – 5x^2 + 6x – x^2 + 5x – 6 = 0
x^3 – 6x^2 + 11x – 6 = 0.
Input: A = 5, B = 2, C = 3
Output: x^3 – 10x^2 + 31x – 30 = 0
Explanation:
Since 5, 2, and 3 are roots of the cubic equations, Then equation is given by:
(x – 5)(x – 2)(x – 3) = 0
(x – 5)(x^2 – 5x + 6) = 0
x^3 – 5x^2 + 6x – 5x^2 + 25x – 30 = 0
x^3 – 10x^2 + 31x – 30 = 0.
Approach: Let the root of the cubic equation (ax3 + bx2 + cx + d = 0) be A, B and C. Then the given cubic equation can be represents as:
ax3 + bx2 + cx + d = x3 – (A + B + C)x2 + (AB + BC +CA)x + A*B*C = 0.
Let X = (A + B + C)
Y = (AB + BC +CA)
Z = A*B*C
Therefore using the above relation find the value of X, Y, and Z and form the required cubic equation.
Below is the implementation of the above approach:
C++
// C++ program for the approach #include <bits/stdc++.h> using namespace std; // Function to find the cubic // equation whose roots are a, b and c void findEquation( int a, int b, int c) { // Find the value of coefficient int X = (a + b + c); int Y = (a * b) + (b * c) + (c * a); int Z = a * b * c; // Print the equation as per the // above coefficients cout << "x^3 - " << X << "x^2 + " << Y << "x - " << Z << " = 0" ; } // Driver Code int main() { int a = 5, b = 2, c = 3; // Function Call findEquation(a, b, c); return 0; } |
Java
// Java program for the approach class GFG{ // Function to find the cubic equation // whose roots are a, b and c static void findEquation( int a, int b, int c) { // Find the value of coefficient int X = (a + b + c); int Y = (a * b) + (b * c) + (c * a); int Z = a * b * c; // Print the equation as per the // above coefficients System.out.print( "x^3 - " + X+ "x^2 + " + Y+ "x - " + Z+ " = 0" ); } // Driver Code public static void main(String[] args) { int a = 5 , b = 2 , c = 3 ; // Function Call findEquation(a, b, c); } } // This code contributed by PrinciRaj1992 |
Python3
# Python3 program for the approach # Function to find the cubic equation # whose roots are a, b and c def findEquation(a, b, c): # Find the value of coefficient X = (a + b + c); Y = (a * b) + (b * c) + (c * a); Z = (a * b * c); # Print the equation as per the # above coefficients print ( "x^3 - " , X , "x^2 + " ,Y , "x - " , Z , " = 0" ); # Driver Code if __name__ = = '__main__' : a = 5 ; b = 2 ; c = 3 ; # Function Call findEquation(a, b, c); # This code is contributed by sapnasingh4991 |
C#
// C# program for the approach using System; class GFG{ // Function to find the cubic equation // whose roots are a, b and c static void findEquation( int a, int b, int c) { // Find the value of coefficient int X = (a + b + c); int Y = (a * b) + (b * c) + (c * a); int Z = a * b * c; // Print the equation as per the // above coefficients Console.Write( "x^3 - " + X + "x^2 + " + Y + "x - " + Z + " = 0" ); } // Driver Code public static void Main() { int a = 5, b = 2, c = 3; // Function Call findEquation(a, b, c); } } // This code is contributed by shivanisinghss2110 |
Javascript
<script> // Javascript program for the approach // Function to find the cubic // equation whose roots are a, b and c function findEquation(a, b, c) { // Find the value of coefficient let X = (a + b + c); let Y = (a * b) + (b * c) + (c * a); let Z = a * b * c; // Print the equation as per the // above coefficients document.write( "x^3 - " + X + "x^2 + " + Y + "x - " + Z + " = 0" ); } let a = 5, b = 2, c = 3; // Function Call findEquation(a, b, c); </script> |
x^3 - 10x^2 + 31x - 30 = 0
Time Complexity: O(1)
Auxiliary Space: O(1)
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