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Home Aptitude Surds and Indices Comments

  • Question
  • If a = ?3/2, then ?1 + a + ?1 - a =?


  • Options
  • A. (2- ?3)
  • B. (2 + ?3)
  • C. ?3/2
  • D. ?3

  • Correct Answer
  • ?3 

    Explanation

    Let us assume
    P = ?1 + a + ?1 - a
    Square on both side,
    P 2 = ( ?1 + a + ?1 - a ) 2
    Use the formula ( a + b ) 2 = a 2 + b 2 + 2ab
    we will get

    ? P 2 = (1 + a) + (1- a) + 2 ?1 + a x ?1 - a
    ? P 2 = (1 + a) + (1- a) + 2 ?(1 + a ) x ( 1 - a )
    ? P 2 = 2 + 2 ?1 - a2
    ? P 2 = 2 (1 + ?1 - a2)
    Now put the value of a which is given in question;
    ? P 2 = 2 (1 + ?1 - ( ?3/2 )2)
    ? P 2 = 2(1 + ?1 - 3/4 )
    ? P 2 = 2(1 + ?1/4 )
    ? P 2 = 2(1 + 1/2) = 2 x 3/2 = 3
    ? P= ?3
    ? (?1 + a + ?1 - a) = ?3


  • Surds and Indices problems


    Search Results


    • 1. 
      If (p/q)n - 1 = (q/p)n - 3, then the value of n is

    • Options
    • A. 1/2
    • B. 7/2
    • C. 1
    • D. 2
    • Discuss
    • 2. 
      If (1/5 )3a = 0.008 Find the value of ( 0.25)a

    • Options
    • A. 20.5
    • B. 22.5
    • C. 0.25
    • D. 6.25
    • Discuss
    • 3. Solve the following:
      ? =?103823

    • Options
    • A. 49
    • B. 51
    • C. 45
    • D. 47
    • Discuss
    • 4. 
      [ (11)3 x (6)2] ÷ (4)3 =?

    • Options
    • A. 2994.75
    • B. 748.6875
    • C. 272.25
    • D. 4492.125
    • Discuss
    • 5. 
      (16)9 ÷ (16)4 x (16)3 = (16)?

    • Options
    • A. 6.75
    • B. 8
    • C. 10
    • D. 12
    • Discuss
    • 6. 
      1/1 + xb - a + xc - a + 1/1 + xa-b + xc - b + 1/1 + xb - c+ xa - c =?

    • Options
    • A. xa - b - c
    • B. 1
    • C. 0
    • D. 3
    • Discuss
    • 7. 
      if a = 2 + ?3, then what is the value of (a2 + a -2)?

    • Options
    • A. 12
    • B. 14
    • C. 16
    • D. 18
    • Discuss
    • 8. 
      If m and n are natural numbers, the m?n

    • Options
    • A. always irrational
    • B. irrational unless n is the mth power of an integer
    • C. irrational unless m is the nthpower of an integer
    • D. irrational unless m and n are coprime
    • Discuss
    • 9. 
      If m = 7 - 4?3, then (?m + 1/?m) =?

    • Options
    • A. 8
    • B. 3
    • C. 4
    • D. 9
    • Discuss
    • 10. 
      If ?2n = 64 , what will be the value of n?

    • Options
    • A. 8
    • B. 4
    • C. 12
    • D. 16
    • Discuss


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