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If a0, a1, a2, a3 are all the positive, ...

If `a_0, a_1, a_2, a_3` are all the positive, then `4a_0x^3+3a_1x^2+2a_2x+a_3=0` has least one root in `(-1,0)` if

A

`a_(0) + a_(2) = a_(1) + a_(3) and 4_(a_(0)) + 2a_(2) gt 3a_(1) + a_(3)`

B

`4a_(0) + 2a_(2) lt 3a_(1) + a _(3)`

C

`4a_(0) + 2a_(2) = 3a_(1) + a_(3) and a_(0) + a_(2) lt a_(1) + a_(3)`

D

none of these

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The correct Answer is:
To determine the conditions under which the polynomial \(4a_0x^3 + 3a_1x^2 + 2a_2x + a_3 = 0\) has at least one root in the interval \((-1, 0)\), we can use the Intermediate Value Theorem. This theorem states that if a continuous function changes sign over an interval, then there exists at least one root in that interval. ### Step-by-Step Solution: 1. **Define the Polynomial**: Let \( p(x) = 4a_0x^3 + 3a_1x^2 + 2a_2x + a_3 \). 2. **Evaluate the Polynomial at the Endpoints**: - Calculate \( p(-1) \): \[ p(-1) = 4a_0(-1)^3 + 3a_1(-1)^2 + 2a_2(-1) + a_3 = -4a_0 + 3a_1 - 2a_2 + a_3 \] - Calculate \( p(0) \): \[ p(0) = a_3 \] 3. **Determine the Sign of \( p(0) \)**: Since \( a_3 > 0 \) (given that all \( a_i \) are positive), we have: \[ p(0) > 0 \] 4. **Set Up the Inequality for \( p(-1) \)**: For \( p(x) \) to have at least one root in \((-1, 0)\), we need: \[ p(-1) < 0 \] This gives us the inequality: \[ -4a_0 + 3a_1 - 2a_2 + a_3 < 0 \] Rearranging this, we get: \[ 4a_0 + 2a_2 > 3a_1 + a_3 \] 5. **Combine with the Condition from Step 3**: Since \( p(0) > 0 \) and \( p(-1) < 0 \), we can conclude that: \[ 4a_0 + 2a_2 > 3a_1 + a_3 \] 6. **Final Condition**: The condition we derived can be expressed as: \[ a_0 + a_2 = a_1 + a_3 \] and \[ 4a_0 + 2a_2 > 3a_1 + a_3 \] This indicates that the first option \( a_0 + a_2 = a_1 + a_3 \) is necessary for the polynomial to have a root in the interval \((-1, 0)\). ### Conclusion: The polynomial \( 4a_0x^3 + 3a_1x^2 + 2a_2x + a_3 = 0 \) has at least one root in the interval \((-1, 0)\) if the condition \( a_0 + a_2 = a_1 + a_3 \) holds true along with the inequality \( 4a_0 + 2a_2 > 3a_1 + a_3 \).

To determine the conditions under which the polynomial \(4a_0x^3 + 3a_1x^2 + 2a_2x + a_3 = 0\) has at least one root in the interval \((-1, 0)\), we can use the Intermediate Value Theorem. This theorem states that if a continuous function changes sign over an interval, then there exists at least one root in that interval. ### Step-by-Step Solution: 1. **Define the Polynomial**: Let \( p(x) = 4a_0x^3 + 3a_1x^2 + 2a_2x + a_3 \). 2. **Evaluate the Polynomial at the Endpoints**: ...
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