Quadratic and cubic equation -show that -(common roots)

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SUMMARY

The discussion centers on proving that if the quadratic equation \( ax^2 + bx + c = 0 \) and the cubic equation \( x^3 + 3x^2 + 3x + 2 = 0 \) share two common roots, then the coefficients must satisfy \( a = b = c \). Participants suggest factoring the cubic equation and using the relationships between the roots and coefficients of both equations. The approach involves verifying that the quadratic is a factor of the cubic and applying Vieta's formulas for both equations to establish the necessary conditions.

PREREQUISITES
  • Understanding of quadratic equations and their properties
  • Familiarity with cubic equations and Vieta's formulas
  • Ability to perform polynomial long division
  • Knowledge of factoring techniques for polynomials
NEXT STEPS
  • Study polynomial long division to factor cubic equations
  • Review Vieta's formulas for both quadratic and cubic equations
  • Practice solving quadratic equations with common roots
  • Explore the implications of common roots in polynomial equations
USEFUL FOR

Students studying algebra, particularly those focusing on polynomial equations, as well as educators looking for examples of common root problems in quadratic and cubic equations.

Sumedh
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Homework Statement



If the equations ax2+bx+c=0 and x3+3x2+3x+2=0 have two common solutions then show a=b=c.

Homework Equations





The Attempt at a Solution



first equation will be the factor of second.
taking out common from first equation.


how to show a=b=c??
please provide hints.
 
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Find a real root of the cubic equation. Write the cubic polynomial as the product of a quadratic factor and a linear factor.
 
Sumedh said:

Homework Statement



If the equations ax2+bx+c=0 and x3+3x2+3x+2=0 have two common solutions then show a=b=c.

Homework Equations


The Attempt at a Solution



first equation will be the factor of second.
taking out common from first equation.how to show a=b=c??
please provide hints.

factorise the cubic.
 
The easiest way to approach this is to divide (x^3 + 3x^2+ 3x + 2) by (x^2 + x +1) to prove that it's a factor. You don't actually need to factorize, just verify that the factor.
 
can we solve by the following formulas

for quadratic eqs.
α+ß =-b/a

αß= c/a

for cubic equations
(Γ=gamma)

α+ß+Γ=-b/a

(αß)+(ßΓ)+(αΓ)=c/a

αßΓ=-d/a



i am trying to solve by this method but i hung up! in between?
 
thank you very much i got it:smile:
 

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