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Find all values of 'm' which (2m-3)x^(2)...

Find all values of 'm' which `(2m-3)x^(2)+2mx+4 lt 0` for all real x.

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To find all values of \( m \) such that the quadratic expression \( (2m-3)x^2 + 2mx + 4 < 0 \) for all real \( x \), we need to analyze the conditions under which a quadratic function is negative for all \( x \). ### Step-by-step Solution: 1. **Identify the coefficients**: The quadratic expression can be written in the standard form \( ax^2 + bx + c \), where: - \( a = 2m - 3 \) - \( b = 2m \) - \( c = 4 \) 2. **Condition for the quadratic to be negative**: For the quadratic \( ax^2 + bx + c < 0 \) to hold for all \( x \): - The coefficient \( a \) must be less than 0 (i.e., the parabola opens downwards). - The discriminant \( D \) must be less than 0 (i.e., there are no real roots). 3. **Set the conditions**: - From \( a < 0 \): \[ 2m - 3 < 0 \implies 2m < 3 \implies m < \frac{3}{2} \] - From the discriminant \( D < 0 \): The discriminant \( D \) is given by \( D = b^2 - 4ac \): \[ D = (2m)^2 - 4(2m - 3)(4) \] Simplifying this: \[ D = 4m^2 - 16(2m - 3) = 4m^2 - 32m + 48 \] Factor out 4: \[ D = 4(m^2 - 8m + 12) \] Now, we need \( m^2 - 8m + 12 < 0 \). 4. **Solve the quadratic inequality**: To find the roots of \( m^2 - 8m + 12 = 0 \): \[ m = \frac{8 \pm \sqrt{(-8)^2 - 4 \cdot 1 \cdot 12}}{2 \cdot 1} = \frac{8 \pm \sqrt{64 - 48}}{2} = \frac{8 \pm \sqrt{16}}{2} = \frac{8 \pm 4}{2} \] This gives us: \[ m = \frac{12}{2} = 6 \quad \text{and} \quad m = \frac{4}{2} = 2 \] The roots are \( m = 2 \) and \( m = 6 \). 5. **Determine the intervals**: The quadratic \( m^2 - 8m + 12 \) opens upwards (as the coefficient of \( m^2 \) is positive). The expression is negative between its roots: \[ 2 < m < 6 \] 6. **Combine the conditions**: We have two conditions: - From \( a < 0 \): \( m < \frac{3}{2} \) - From \( D < 0 \): \( 2 < m < 6 \) The first condition \( m < \frac{3}{2} \) does not overlap with the second condition \( 2 < m < 6 \). Therefore, there are no values of \( m \) that satisfy both conditions simultaneously. ### Conclusion: There are no values of \( m \) such that \( (2m-3)x^2 + 2mx + 4 < 0 \) for all real \( x \).
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Knowledge Check

  • Find the value of m if (2)/(3) is a solution of the equation 3x^(2) + mx + 2 = 0

    A
    `-2sqrt6`
    B
    `-5`
    C
    `-2sqrt3`
    D
    -6
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