# Quadratic equation whose roots are reciprocal to the roots of given equation

• Difficulty Level : Basic
• Last Updated : 22 Apr, 2021

Given three integers A, B, and C representing the coefficients of a quadratic equation Ax2 + Bx + C = 0, the task is to find the quadratic equation whose roots are reciprocal to the roots of the given equation.

Examples:

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Input: A = 1, B = -5, C = 6
Output: (6)x^2 +(-5)x + (1) = 0
Explanation:
The given quadratic equation x2 – 5x + 6 = 0.
Roots of the above equation are 2, 3.
Reciprocal of these roots are 1/2, 1/3.
Therefore, the quadratic equation with these reciprocal roots is 6x2 – 5x + 1 = 0.

Input: A = 1, B = -7, C = 12
Output: (12)x^2 +(-7)x + (1) = 0

Approach: The idea is to use the concept of quadratic roots to solve the problem. Follow the steps below to solve the problem:

• Consider the roots of the equation Ax2 + Bx + C = 0 to be p, q.
• The product of the roots of the above equation is given by p * q = C / A.
• The sum of the roots of the above equation is given by p + q = -B / A.
• Therefore, the reciprocals of the roots are 1/p, 1/q.
• The product of these reciprocal roots is 1/p * 1/q = A / C.
• The sum of these reciprocal roots is 1/p + 1/q = -B / C.
• If the sum and product of roots is known, the quadratic equation can be x2 – (Sum of the roots)x + (Product of the roots) = 0.
• On solving the above equation, quadratic equation becomes Cx2 + Bx + A = 0.

Below is the implementation of the above approach:

## C++

 `// C++ program for the above approach`   `#include ` `using` `namespace` `std;`   `// Function to find the quadratic` `// equation having reciprocal roots` `void` `findEquation(``int` `A, ``int` `B, ``int` `C)` `{` `    ``// Print quadratic equation` `    ``cout << ``"("` `<< C << ``")"` `         ``<< ``"x^2 +("` `<< B << ``")x + ("` `         ``<< A << ``") = 0"``;` `}`   `// Driver Code` `int` `main()` `{` `    ``// Given coefficients` `    ``int` `A = 1, B = -5, C = 6;`   `    ``// Function call to find the quadratic` `    ``// equation having reciprocal roots` `    ``findEquation(A, B, C);`   `    ``return` `0;` `}`

## Java

 `// Java program for the above approach` `class` `GFG{` ` `  `// Function to find the quadratic` `// equation having reciprocal roots` `static` `void` `findEquation(``int` `A, ``int` `B, ``int` `C)` `{` `    `  `    ``// Print quadratic equation` `    ``System.out.print(``"("` `+ C + ``")"` `+  ` `                ``"x^2 +("` `+ B + ``")x + ("` `+` `                           ``A + ``") = 0"``);` `}`   `// Driver Code` `public` `static` `void` `main(String args[])` `{` `    `  `    ``// Given coefficients` `    ``int` `A = ``1``, B = -``5``, C = ``6``;`   `    ``// Function call to find the quadratic` `    ``// equation having reciprocal roots` `    ``findEquation(A, B, C);` `}` `}`   `// This code is contributed by AnkThon`

## Python3

 `# Python3 program for the above approach`   `# Function to find the quadratic` `# equation having reciprocal roots` `def` `findEquation(A, B, C):` `    `  `    ``# Print quadratic equation` `    ``print``(``"("` `+` `str``(C)  ``+` `")"` `+` `     ``"x^2 +("` `+` `str``(B) ``+` `")x + ("` `+` `                ``str``(A) ``+` `") = 0"``)`   `# Driver Code` `if` `__name__ ``=``=` `"__main__"``:` `    `  `    ``# Given coefficients` `    ``A ``=` `1` `    ``B ``=` `-``5` `    ``C ``=` `6`   `    ``# Function call to find the quadratic` `    ``# equation having reciprocal roots` `    ``findEquation(A, B, C)`   `# This code is contributed by AnkThon`

## C#

 `// C# program for the above approach` `using` `System;` `using` `System.Collections.Generic;`   `class` `GFG{` ` `  `// Function to find the quadratic` `// equation having reciprocal roots` `static` `void` `findEquation(``int` `A, ``int` `B, ``int` `C)` `{` `    ``// Print quadratic equation` `    ``Console.Write(``"("` `+ C + ``")"` `+  ` `             ``"x^2 +("` `+ B + ``")x + ("` `+` `                        ``A + ``") = 0"``);` `}`   `// Driver Code` `public` `static` `void` `Main()` `{` `    `  `    ``// Given coefficients` `    ``int` `A = 1, B = -5, C = 6;`   `    ``// Function call to find the quadratic` `    ``// equation having reciprocal roots` `    ``findEquation(A, B, C);` `}` `}`   `// This code is contributed by bgangwar59`

## Javascript

 ``

Output:

`(6)x^2 +(-5)x + (1) = 0`

Time Complexity: O(1)
Auxiliary Space: O(1)

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