Can Absolute Values of Quadratic Functions Determine Their Discriminants?

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SUMMARY

The discussion centers on the relationship between the absolute values of quadratic functions and their discriminants. Specifically, it establishes that if the inequality $$ \left| f(x) \right| \ge \left| g(x) \right| $$ holds for all real $$ x$$, then it follows that $$ \left| \Delta_f \right| \ge \left| \Delta_g \right|$$, where $$ \Delta $$ represents the discriminant defined as $$ \Delta = b^2 - 4ac $$ for a quadratic function $$ f(x) = ax^2 + bx + c $$. The problem was initially posed as a challenge by a user named anemone, and a solution is available in the forum thread.

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  • Familiarity with absolute value inequalities
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  • Learn about the significance of the discriminant in determining the nature of roots
  • Explore absolute value inequalities and their applications in algebra
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Mathick
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Let $$ f(x)$$ and $$ g(x)$$ be quadratic functions such as the inequality $$ \left| f(x) \right| \ge \left| g(x) \right| $$ is hold for all real $$ x$$ . Prove that $$ \left| \Delta_f \right| \ge \left| \Delta_g \right|$$. For quadratic function $$ f(x)=ax^2+bx+c $$, then $$ \Delta=b^2-4ac. $$

I have no idea how I could start this task. Please, help!
 
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Hi Mathick,

This was actually a challenge problem that anemone posted http://mathhelpboards.com/challenge-questions-puzzles-28/prove-b-4ac-8804-b-4ac-15129.html. A solution is provided in the last post.
 

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