Math Problem Statement

Solve real number m element of R so that 2xx-5x+2m=0 has complex solution and (m+5)xx+3x-1=0 has double solution

Solution

To solve for the real number mRm \in \mathbb{R} such that the given conditions hold, let's break the problem into two parts and solve step-by-step:


1. Condition 1: The equation 2x25x+2m=02x^2 - 5x + 2m = 0 has complex solutions.

For a quadratic equation ax2+bx+c=0ax^2 + bx + c = 0 to have complex solutions, its discriminant (Δ\Delta) must satisfy:

Δ=b24ac<0\Delta = b^2 - 4ac < 0

Here: a=2,b=5,c=2ma = 2, \quad b = -5, \quad c = 2m

The discriminant is: Δ=(5)24(2)(2m)=2516m\Delta = (-5)^2 - 4(2)(2m) = 25 - 16m

For complex solutions: 2516m<0m>251625 - 16m < 0 \quad \Rightarrow \quad m > \frac{25}{16}


2. Condition 2: The equation (m+5)x2+3x1=0(m+5)x^2 + 3x - 1 = 0 has a double solution.

For a quadratic equation to have a double solution, its discriminant (Δ\Delta) must equal zero:

Δ=b24ac=0\Delta = b^2 - 4ac = 0

Here: a=m+5,b=3,c=1a = m+5, \quad b = 3, \quad c = -1

The discriminant is: Δ=324(m+5)(1)=9+4(m+5)\Delta = 3^2 - 4(m+5)(-1) = 9 + 4(m+5)

For a double solution: 9+4(m+5)=04(m+5)=9m+5=949 + 4(m+5) = 0 \quad \Rightarrow \quad 4(m+5) = -9 \quad \Rightarrow \quad m+5 = -\frac{9}{4}

Solving for mm: m=945=94204=294m = -\frac{9}{4} - 5 = -\frac{9}{4} - \frac{20}{4} = -\frac{29}{4}


3. Combine the conditions:

From Condition 1: m>2516m > \frac{25}{16}.

From Condition 2: m=294m = -\frac{29}{4}.

There is no mm that satisfies both conditions simultaneously.


Conclusion:

There is no real value of mm such that both conditions hold true. The problem has no solution in R\mathbb{R}.


Follow-up Questions:

  1. What happens if we modify the first condition to allow real roots?
  2. How does the discriminant determine the nature of roots for quadratic equations?
  3. What if the second equation has distinct real roots instead of a double solution?
  4. Can we visualize the solution space for mm in both conditions graphically?
  5. How can we derive similar conditions for cubic equations?

Tip:

When dealing with quadratic equations, always start by analyzing the discriminant to determine the nature of the roots.

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Math Problem Analysis

Mathematical Concepts

Algebra
Quadratic Equations
Discriminant Analysis

Formulas

Discriminant formula: Δ = b^2 - 4ac
Conditions for complex solutions: Δ < 0
Conditions for double roots: Δ = 0

Theorems

Discriminant Theorem

Suitable Grade Level

Grades 10-12