Maths - a proof question on the nature of roots of quadratic equations

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SUMMARY

The discussion focuses on proving the inequality \(s^2 - 4s - 12 \geq 0\) given the expression \(s = \frac{4(x^2) + 3}{2x - 1}\). Participants emphasize the necessity of transforming the expression for \(s\) into a standard quadratic form to apply the discriminant condition, \(b^2 - 4ac \geq 0\). The key steps involve identifying coefficients \(a\), \(b\), and \(c\) from the quadratic equation derived from the inequality. This approach ensures that the roots of the quadratic are real and satisfy the given condition.

PREREQUISITES
  • Understanding of quadratic equations and their properties
  • Familiarity with the discriminant and its role in determining the nature of roots
  • Basic algebraic manipulation skills
  • Knowledge of rational functions and their behavior
NEXT STEPS
  • Study the properties of quadratic equations, focusing on the discriminant
  • Learn how to manipulate rational expressions to form quadratics
  • Explore examples of proving inequalities involving quadratics
  • Practice solving real-world problems using quadratic inequalities
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Students studying algebra, particularly those tackling quadratic equations and inequalities, as well as educators looking for examples to illustrate these concepts.

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I'm sorry, I just realized I put this in the wrong subsection. While I figure out how to fix that, please have a look anyway.
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Homework Statement



Given x \inℝ
And s =\frac{4(x^{2}) + 3}{2x-1}
Prove that s^{2} -4s - 12 ≥ 0

Homework Equations


The discriminant Δ, (in order for which to be real must be ≥ 0)
b^2 - 4ac ≥ 0

The Attempt at a Solution


Doing the algebra isn't the problem, I'm having trouble understanding the question itself. For this sort of proof, don't I need to work with
s =\frac{4(x^{2}) + 3}{2x-1}
instead of the statement to be proven, which is s^{2} -4s - 12 ≥ 0?

In which case, how do I apply the b^2 - 4ac rule with the linear equation part in the denominator?
 
Last edited:
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The variable is ##x##, so make the given equation look like a regular quadratic in ##x##. Then pick off what ##a##, ##b##, and ##c## are and write the inequality for ##\Delta## in terms of those. It will quickly resolve into what's requested.
 

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