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The value of a for which the quadratic e...

The value of `a` for which the quadratic equation
`3x^(2) + 2a^(2) + 1x + a^(2) - 3a + 2 = 0`
Possesses roots of opposite signs lies in

A

`(-infty, 1)`

B

`(-infty, 0)`

C

`(1, 2)`

D

`(3/2, 2)`

Text Solution

AI Generated Solution

The correct Answer is:
To find the value of \( a \) for which the quadratic equation \[ 3x^2 + (2a^2 + 1)x + (a^2 - 3a + 2) = 0 \] has roots of opposite signs, we can follow these steps: ### Step 1: Identify the roots' product condition For a quadratic equation \( ax^2 + bx + c = 0 \), the product of the roots \( \alpha \) and \( \beta \) is given by \[ \alpha \beta = \frac{c}{a} \] In our case, \( a = 3 \), \( b = 2a^2 + 1 \), and \( c = a^2 - 3a + 2 \). Therefore, we have: \[ \alpha \beta = \frac{a^2 - 3a + 2}{3} \] ### Step 2: Condition for opposite signs For the roots to have opposite signs, their product must be negative: \[ \frac{a^2 - 3a + 2}{3} < 0 \] This simplifies to: \[ a^2 - 3a + 2 < 0 \] ### Step 3: Factor the quadratic expression Next, we factor the quadratic expression: \[ a^2 - 3a + 2 = (a - 1)(a - 2) \] ### Step 4: Solve the inequality Now we need to solve the inequality: \[ (a - 1)(a - 2) < 0 \] ### Step 5: Determine the intervals To find the intervals where the product is negative, we can test the intervals determined by the roots \( a = 1 \) and \( a = 2 \): - For \( a < 1 \): Choose \( a = 0 \) → \( (0 - 1)(0 - 2) = 2 > 0 \) (positive) - For \( 1 < a < 2 \): Choose \( a = 1.5 \) → \( (1.5 - 1)(1.5 - 2) = (0.5)(-0.5) = -0.25 < 0 \) (negative) - For \( a > 2 \): Choose \( a = 3 \) → \( (3 - 1)(3 - 2) = 2 > 0 \) (positive) Thus, the inequality \( (a - 1)(a - 2) < 0 \) holds true in the interval: \[ 1 < a < 2 \] ### Conclusion The values of \( a \) for which the quadratic equation possesses roots of opposite signs lie in the interval \( (1, 2) \). ---
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