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Solve the equation 3x^3 -26 x^2 +...

Solve the equation
` 3x^3 -26 x^2 + 52 x-24 =0`
the roots being in G.P

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To solve the equation \( 3x^3 - 26x^2 + 52x - 24 = 0 \) with roots in Geometric Progression (G.P.), we can follow these steps: ### Step 1: Define the Roots Let the roots of the equation be \( \frac{a}{r}, a, ar \), where \( a \) is a constant and \( r \) is the common ratio. ### Step 2: Use the Product of Roots According to Vieta's formulas, the product of the roots of a cubic equation \( ax^3 + bx^2 + cx + d = 0 \) is given by: \[ \text{Product of roots} = -\frac{d}{a} \] For our equation: - \( a = 3 \) - \( d = -24 \) Thus, the product of the roots is: \[ \frac{a}{r} \cdot a \cdot ar = a^3 \] Setting this equal to \(-\frac{-24}{3} = 8\): \[ a^3 = 8 \implies a = 2 \] ### Step 3: Use the Sum of Roots The sum of the roots is given by: \[ \frac{a}{r} + a + ar = -\frac{b}{a} \] For our equation: - \( b = -26 \) Thus, the sum of the roots is: \[ \frac{2}{r} + 2 + 2r = \frac{26}{3} \] Multiplying through by \( r \) to eliminate the fraction gives: \[ 2 + 2r + 2r^2 = \frac{26}{3}r \] Rearranging this leads to: \[ 2r^2 - \frac{26}{3}r + 2 = 0 \] Multiplying through by 3 to clear the fraction: \[ 6r^2 - 26r + 6 = 0 \] ### Step 4: Solve the Quadratic Equation Now we can solve the quadratic equation \( 6r^2 - 26r + 6 = 0 \) using the quadratic formula: \[ r = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] Here, \( a = 6, b = -26, c = 6 \): \[ r = \frac{26 \pm \sqrt{(-26)^2 - 4 \cdot 6 \cdot 6}}{2 \cdot 6} \] Calculating the discriminant: \[ r = \frac{26 \pm \sqrt{676 - 144}}{12} = \frac{26 \pm \sqrt{532}}{12} = \frac{26 \pm 2\sqrt{133}}{12} = \frac{13 \pm \sqrt{133}}{6} \] ### Step 5: Find the Roots Now substituting the values of \( r \) back into the roots: 1. For \( r_1 = \frac{13 + \sqrt{133}}{6} \) 2. For \( r_2 = \frac{13 - \sqrt{133}}{6} \) The roots of the equation are: \[ \frac{2}{r_1}, 2, 2r_1 \quad \text{and} \quad \frac{2}{r_2}, 2, 2r_2 \] ### Final Roots Thus, the roots of the equation \( 3x^3 - 26x^2 + 52x - 24 = 0 \) are: - \( \left( \frac{2}{\frac{13 + \sqrt{133}}{6}}, 2, 2 \cdot \frac{13 + \sqrt{133}}{6} \right) \) - \( \left( \frac{2}{\frac{13 - \sqrt{133}}{6}}, 2, 2 \cdot \frac{13 - \sqrt{133}}{6} \right) \)
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