यदि समीकरण x2 – x – 1 = 0 के मूल α और β हैं, तब α/β और β/α मूल वाला समीकरण क्या होगा?

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RRC Group D Previous Paper 2 (Held On: 18 Sep 2018 Shift 1)
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  1. x2 + 3x – 1 = 0
  2. x2 + x – 1 = 0
  3. x2 – x + 1 = 0
  4. x2 + 3x + 1 = 0

Answer (Detailed Solution Below)

Option 4 : x2 + 3x + 1 = 0
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दिया हुआ:

x2 - x - 1 = 0

उपयोग किया गया सूत्र:

यदि दिए गए समीकरण ax2 + bx + c = 0 है

फिर मूलों का योग = -b/a

मूलों का गुणनफल = c/a

गणना:

चूंकि समीकरण x2 – x – 1 = 0 के मूल α और β हैं, तब

⇒ α + β = -(-1) = 1

⇒ αβ = -1

अब, यदि (α/β) और (β/α) मूल हैं तब,

⇒ मूलों का योग = (α/β) + (β/α)

⇒ मूलों का योग = (α2 + β2)/αβ

⇒ मूलों का योग = {(α + β)2 – 2αβ}/αβ

⇒ मूलों का योग = {(1)2 – 2(-1)}/(-1) = -3

⇒ मूलों का गुणनफल = (α/β) × (β/α) = 1

अब, समीकरण है,

⇒ x2 – (मूलों का योग)x + मूलों का गुणनफल = 0

⇒ x2 – (-3)x + (1) = 0

⇒ x2 + 3x + 1 = 0
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