Math Problem Statement

Solve question 9

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

Solution

The question asks to "find the range of values of mm for which the quadratic equation mx2+mx2=0mx^2 + mx - 2 = 0 has one or two real roots."

Solution:

The general quadratic equation is: ax2+bx+c=0ax^2 + bx + c = 0 For the equation mx2+mx2=0mx^2 + mx - 2 = 0, the coefficients are:

  • a=ma = m
  • b=mb = m
  • c=2c = -2

To find the nature of the roots (real, equal, or imaginary), we use the discriminant Δ\Delta formula: Δ=b24ac\Delta = b^2 - 4ac In this case: Δ=m24(m)(2)\Delta = m^2 - 4(m)(-2) Δ=m2+8m\Delta = m^2 + 8m

For the quadratic equation to have one or two real roots, the discriminant must be non-negative: Δ0\Delta \geq 0 m2+8m0m^2 + 8m \geq 0

Solving the inequality:

Factor the expression: m(m+8)0m(m + 8) \geq 0

This quadratic inequality can be solved by analyzing the critical points, m=0m = 0 and m=8m = -8, which divide the number line into intervals. We test each interval to determine where the product is non-negative.

  1. For m<8m < -8: Both factors are negative, so the product is positive.
  2. For 8<m<0-8 < m < 0: One factor is negative and the other is positive, so the product is negative.
  3. For m>0m > 0: Both factors are positive, so the product is positive.

Thus, the quadratic inequality holds when m(,8][0,)m \in (-\infty, -8] \cup [0, \infty).

Conclusion:

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


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Math Problem Analysis

Mathematical Concepts

Quadratic equations
Discriminants
Inequalities

Formulas

Discriminant formula: Delta = b^2 - 4ac

Theorems

The nature of roots depends on the discriminant: Delta > 0 (two real roots), Delta = 0 (one real root), Delta < 0 (no real roots)

Suitable Grade Level

Grades 9-10