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Transform the following equation into an equation whose roots are four times those of given equation 3x3 - 2x2 - x + 1 = 0. |
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Answer» Given equation is 3x3 - 2x2 - x + 1 = 0----(1) Let α, ß, γ are root of equation (1) \(\therefore\) Sum of roots = -b/a = -(-2)/3 = 2/3 ⇒ α + ß + γ = 2/3 ----(2) sum of product of two roots = c/a = -1/3 ⇒ αß + ßγ + γα = -1/3----(3) ⇒ αßγ = -1/3 ---(4) Now, 4α + 4ß + 4γ = 4(α + ß + γ) = 4 x 2/3 = 8/3 (From 2) 4α .4ß + 4ß.4γ + 4γ. 4α = 16(αß + ßγ + γα) = 16 x -1/3 = -16/3 (From 3) 4α. 4ß. 4γ = 64αßγ = 64 x -1/3 = -64/3 (From (4)) \(\therefore\) Required equation whose roots are 4 times than given roots is x3 - (sum of roots)x2 + (sum of products of two roots)x - (products of roots) = 0 ⇒ x3 - (8/3)x2 = (16/3) x - \((-64/3)=0\) ⇒ 3x3 - 8x2 - 16x + 64 = 0 which is required equation. |
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