जर \(\rm x-\frac{1}{x}=-6\) आहे , तर \(\rm x^5-\frac{1}{x^5}\) चे मूल्य काय असेल?

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Question

This question was previously asked in

SSC CGL 2023 Tier-I Official Paper (Held On: 18 Jul 2023 Shift 2)

Answer 1

दिलेले आहे:

x - (1/x) = (- 6)

वापरलेले सूत्र:

जर x - (1/x) = P, तर

x + (1/x) = √(P2 + 4)

जर x + (1/x) = P, तर

x3 + (1/x3) = (P3 - 3P)

x5 - (1/x5) = {x3 + (1/x3)} × {x2 - 1/x2} + {x - (1/x)}

गणना:

x - (1/x) = (- 6)

x + (1/x) = √{(- 6)2 + 4} = √40 = 2√10

अशाप्रकारे, x2 - 1/x2 = (x + 1/x) (x - 1/x) = 2√10 × (-6) = -12√10

आणि x3 + (1/x3) = (√40)3 - 3√40

⇒ 40√40 - 3√40 = 37 × 2√10 = 74√10

आता,

x5 - (1/x5) = {x3 + (1/x3)} × {x2 - 1/x2} + {x - (1/x)}

⇒ {74√10 × (-12√10)} + (- 6)

⇒ - 74 × 12 × (√10 × √10) - 6

⇒ (- 8880) - 6 = - 8886

∴ योग्य उत्तर - 8886 आहे.

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