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if allvalues of x which satisfies the inequality `log _((1//3))(x ^(2) +2px+p^(2) +1) ge 0` also satisfy the inequality `kx ^(2)+kx- k ^(2) le 0` for all real values of k, then all possible values of p lies in the interval :

A

`[-1,1]`

B

`[0,1]`

C

`[0,2]`

D

`[-2,0]`

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The correct Answer is:
To solve the problem step by step, we need to analyze the two inequalities given in the question. ### Step 1: Analyze the first inequality The first inequality is given as: \[ \log_{(1/3)}(x^2 + 2px + p^2 + 1) \geq 0 \] This implies that: \[ x^2 + 2px + p^2 + 1 \leq 1 \] because the logarithm is non-negative when its argument is less than or equal to 1 for a base less than 1. ### Step 2: Simplify the first inequality Rearranging the inequality: \[ x^2 + 2px + p^2 + 1 - 1 \leq 0 \] This simplifies to: \[ x^2 + 2px + p^2 \leq 0 \] This is a quadratic inequality in \(x\). ### Step 3: Determine the conditions for the quadratic inequality The quadratic \(x^2 + 2px + p^2\) can be factored as: \[ (x + p)^2 \leq 0 \] The expression \((x + p)^2\) is a perfect square and is non-negative. It equals zero only when: \[ x + p = 0 \implies x = -p \] Thus, the only solution to the inequality \(x^2 + 2px + p^2 \leq 0\) is: \[ x = -p \] ### Step 4: Analyze the second inequality The second inequality is: \[ kx^2 + kx - k^2 \leq 0 \] Factoring this gives: \[ k(x^2 + x - k) \leq 0 \] This is a quadratic in \(x\) which will have real roots if the discriminant is non-negative. ### Step 5: Find the discriminant of the second inequality The discriminant \(D\) of the quadratic \(x^2 + x - k\) is given by: \[ D = 1^2 - 4(1)(-k) = 1 + 4k \] For the quadratic to have real roots, we need: \[ 1 + 4k \geq 0 \implies k \geq -\frac{1}{4} \] ### Step 6: Substitute \(x = -p\) into the second inequality Substituting \(x = -p\) into the second inequality: \[ k((-p)^2 + (-p) - k) \leq 0 \] This simplifies to: \[ k(p^2 - p - k) \leq 0 \] ### Step 7: Analyze the quadratic in \(k\) The quadratic \(p^2 - p - k\) must be non-positive for all \(k\). This means the quadratic must open upwards (coefficient of \(k\) is positive) and have its vertex above or on the x-axis. ### Step 8: Find the conditions for \(p\) The vertex of the quadratic \(p^2 - p - k\) occurs at: \[ k = \frac{p^2 - p}{2} \] For the quadratic to be non-positive for all \(k\), the discriminant must be non-positive: \[ (-1)^2 - 4(1)(p^2) \leq 0 \] This gives: \[ 1 - 4p^2 \leq 0 \implies 4p^2 \geq 1 \implies p^2 \geq \frac{1}{4} \implies |p| \geq \frac{1}{2} \] ### Step 9: Determine the interval for \(p\) Thus, the possible values of \(p\) lie in the intervals: \[ p \leq -\frac{1}{2} \quad \text{or} \quad p \geq \frac{1}{2} \] ### Conclusion The final answer is that all possible values of \(p\) lie in the intervals: \[ (-\infty, -\frac{1}{2}] \cup [\frac{1}{2}, \infty) \]
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