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If `alpha` is a the absolute maximum value of the expression `(3x^(2)+2x-1)/(x^(2)+x+1)AA x in R`, then `[alpha]` is ______________. (where `[.]` denotes the greatest integer function)

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To find the absolute maximum value of the expression \(\frac{3x^2 + 2x - 1}{x^2 + x + 1}\) for \(x \in \mathbb{R}\), we will follow these steps: ### Step 1: Set the expression equal to \(k\) Let: \[ y = \frac{3x^2 + 2x - 1}{x^2 + x + 1} = k \] This implies: \[ 3x^2 + 2x - 1 = k(x^2 + x + 1) \] ### Step 2: Rearrange the equation Rearranging gives: \[ 3x^2 + 2x - 1 - kx^2 - kx - k = 0 \] This simplifies to: \[ (3 - k)x^2 + (2 - k)x + (-1 - k) = 0 \] ### Step 3: Find the condition for real roots For \(x\) to be real, the discriminant of this quadratic must be non-negative: \[ D = (2 - k)^2 - 4(3 - k)(-1 - k) \geq 0 \] Calculating the discriminant: \[ D = (2 - k)^2 - 4(3 - k)(-1 - k) \] Expanding this: \[ D = (2 - k)^2 + 4(3 - k)(1 + k) \] \[ = (2 - k)^2 + 4(3 + 3k - k - k^2) \] \[ = (2 - k)^2 + 4(3 + 2k - k^2) \] ### Step 4: Set the discriminant greater than or equal to zero Now we need to solve: \[ (2 - k)^2 + 4(3 + 2k - k^2) \geq 0 \] ### Step 5: Simplify the inequality Expanding and simplifying: \[ (2 - k)^2 + 12 + 8k - 4k^2 \geq 0 \] This leads to: \[ -k^2 + 6k + 16 \geq 0 \] Rearranging gives: \[ k^2 - 6k - 16 \leq 0 \] ### Step 6: Find the roots of the quadratic Using the quadratic formula: \[ k = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} = \frac{6 \pm \sqrt{36 + 64}}{2} = \frac{6 \pm 10}{2} \] This gives: \[ k = 8 \quad \text{and} \quad k = -2 \] ### Step 7: Determine the interval for \(k\) The inequality \(k^2 - 6k - 16 \leq 0\) holds between the roots: \[ -2 \leq k \leq 8 \] ### Step 8: Find the maximum value of \(k\) The maximum value of \(k\) is \(8\). ### Step 9: Apply the greatest integer function Thus, the absolute maximum value \(\alpha = 8\). The greatest integer function \([ \alpha ]\) is: \[ [ \alpha ] = [8] = 8 \] ### Final Answer The answer is: \[ \boxed{8} \]
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