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If both the roots of the equation 4x^(2)...

If both the roots of the equation `4x^(2)-2x+m=0` lie in the interval `(-1, 1)`, then

A

`-3 lt m lt -2`

B

`0 lt m lt 2`

C

`2lt m lt (5)/(2)`

D

`-2 lt m le (1)/(4)`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the values of \( m \) such that both roots of the quadratic equation \( 4x^2 - 2x + m = 0 \) lie in the interval \( (-1, 1) \). ### Step 1: Identify the conditions for the roots For the roots of the quadratic equation to lie within the interval \( (-1, 1) \), the function must be positive at the endpoints of the interval. Therefore, we need to check: 1. \( f(-1) > 0 \) 2. \( f(1) > 0 \) ### Step 2: Calculate \( f(-1) \) Substituting \( x = -1 \) into the function: \[ f(-1) = 4(-1)^2 - 2(-1) + m = 4(1) + 2 + m = 4 + 2 + m = m + 6 \] For \( f(-1) > 0 \): \[ m + 6 > 0 \implies m > -6 \] ### Step 3: Calculate \( f(1) \) Substituting \( x = 1 \) into the function: \[ f(1) = 4(1)^2 - 2(1) + m = 4(1) - 2 + m = 4 - 2 + m = m + 2 \] For \( f(1) > 0 \): \[ m + 2 > 0 \implies m > -2 \] ### Step 4: Calculate the discriminant For the roots to be real, the discriminant of the quadratic must be non-negative: \[ D = b^2 - 4ac = (-2)^2 - 4(4)(m) = 4 - 16m \] Setting the discriminant greater than or equal to zero: \[ 4 - 16m \geq 0 \implies 4 \geq 16m \implies \frac{1}{4} \geq m \implies m \leq \frac{1}{4} \] ### Step 5: Combine the conditions We have three conditions: 1. \( m > -6 \) 2. \( m > -2 \) 3. \( m \leq \frac{1}{4} \) The most restrictive conditions are \( m > -2 \) and \( m \leq \frac{1}{4} \). ### Step 6: Final result Thus, the values of \( m \) must satisfy: \[ -2 < m \leq \frac{1}{4} \] ### Conclusion The final answer is: \[ m \in (-2, \frac{1}{4}] \]
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