Math Problem Statement
if k is a positive integer, find the maximum value of k such that (k+8)x² + (k-2)x-3=0 has real roots
Solution
To find the maximum value of such that the quadratic equation
has real roots, we need to ensure that the discriminant of the equation is non-negative.
Step 1: Identify the Discriminant Condition for Real Roots
For a quadratic equation of the form , the discriminant is given by:
The roots are real if and only if .
Step 2: Define , , and
In our equation:
Step 3: Compute the Discriminant
Substitute these values into the discriminant formula:
Expanding this:
Calculate each term:
So,
Combine like terms:
Step 4: Ensure the Discriminant is Non-negative
For the quadratic equation to have real roots, we need:
Step 5: Analyze the Quadratic Expression
The expression is always positive for all values of since its discriminant () is negative, indicating it has no real roots and opens upwards.
Therefore, no upper limit on is needed for real roots to exist. The value of can be any positive integer.
Conclusion
The maximum value of such that has real roots is unbounded, meaning can be any positive integer.
Would you like further clarification on any part of the solution?
Related Questions:
- What if were negative? How would the result change?
- How would we find the roots if were a specific value, like 1 or 2?
- Could there be any conditions on for complex roots to occur?
- What if we were asked for integer solutions for given this quadratic?
- How would this change if we maximized for complex roots instead?
Tip: For any quadratic equation, always check the discriminant to determine the nature of its roots.
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Math Problem Analysis
Mathematical Concepts
Algebra
Quadratic Equations
Discriminant
Formulas
Discriminant formula for quadratic equations: Δ = b² - 4ac
Theorems
Real Roots Theorem (discriminant condition)
Suitable Grade Level
Grades 10-12
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