Math Problem Statement

find the range of values of m for which the equation mx^2 + mx - 2 = 0 has one or two real roots.

Solution

To determine the range of values of mm for which the equation mx2+mx2=0mx^2 + mx - 2 = 0 has one or two real roots, we analyze the discriminant (Δ\Delta) of the quadratic equation.

General Quadratic Equation and Discriminant:

For a quadratic equation ax2+bx+c=0ax^2 + bx + c = 0, the discriminant is: Δ=b24ac\Delta = b^2 - 4ac The nature of the roots depends on Δ\Delta:

  1. Δ>0\Delta > 0: Two distinct real roots.
  2. Δ=0\Delta = 0: One real root (repeated root).
  3. Δ<0\Delta < 0: No real roots (complex roots).

Step-by-Step Solution:

For the given equation mx2+mx2=0mx^2 + mx - 2 = 0:

  • Coefficient of x2x^2: a=ma = m
  • Coefficient of xx: b=mb = m
  • Constant term: c=2c = -2

The discriminant is: Δ=b24ac=m24(m)(2)\Delta = b^2 - 4ac = m^2 - 4(m)(-2)

Simplify: Δ=m2+8m\Delta = m^2 + 8m

Condition for One or Two Real Roots:

  1. At least one real root exists if Δ0\Delta \geq 0: m2+8m0m^2 + 8m \geq 0

    Factorize: m(m+8)0m(m + 8) \geq 0

    Solve the inequality:

    • The critical points are m=0m = 0 and m=8m = -8.
    • Test intervals around m=0m = 0 and m=8m = -8:
      • For m<8m < -8: m(m+8)>0m(m + 8) > 0.
      • For 8<m<0-8 < m < 0: m(m+8)<0m(m + 8) < 0.
      • For m>0m > 0: m(m+8)>0m(m + 8) > 0.

    The solution to m(m+8)0m(m + 8) \geq 0 is: m(,8][0,)m \in (-\infty, -8] \cup [0, \infty)

Final Answer:

The equation mx2+mx2=0mx^2 + mx - 2 = 0 has one or two real roots if: m(,8][0,)m \in (-\infty, -8] \cup [0, \infty)

Would you like further details on solving quadratic inequalities or interpreting discriminants? Let me know!


Related Questions:

  1. How do you solve quadratic equations when Δ=0\Delta = 0?
  2. What is the significance of the sign of aa in quadratic equations?
  3. How do you graphically represent quadratic inequalities like m(m+8)0m(m + 8) \geq 0?
  4. What happens to the roots if Δ<0\Delta < 0?
  5. How can the vertex form of a quadratic equation help in analyzing roots?

Tip:

Always check the coefficient of x2x^2 (aa) in a quadratic equation—if a=0a = 0, the equation becomes linear!

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Discriminants
Inequalities

Formulas

Discriminant formula: \Delta = b^2 - 4ac
Inequality solving: m(m + 8) \geq 0

Theorems

Discriminant Theorem for quadratic equations

Suitable Grade Level

Grades 9-11