Surds and Indices


  1. 56 + √56 + 56 + .... ) ÷ 22 = ?









  1. View Hint View Answer Discuss in Forum

    Here, Let us Assume ,
    p = √56 + √56 + 56 + ...........
    p = √56 + p
    Square on both side and solve the above equation.

    Correct Option: C

    Here, Let us Assume ,
    p = √56 + √56 + 56 + ...........
    p = √56 + p
    Square on both side and solve the above equation.
    p2= 56 + p
    p2 - p= 56
    p(p - 1 ) = 56
    p(p - 1 ) = 8 x 7
    ⇒ Either p = 8 or p - 1 = 7
    ⇒ So p = 8;
    Now given equation in question is
    56 + √56 + 56 + .... ) ÷ 22 = ?
    p ÷ 22 = ?
    Put the value of p
    8 ÷ 22 = ?
    8 ÷ 4 = ?
    ? = 2;


  1. Find the value of m - n, if ( 9n x 32 x (3-n/2)-2 - (27)n ) / ( 33m x 23 ) = 1/27 ?









  1. View Hint View Answer Discuss in Forum

    ( 9n x 32 x (3-n/2)-2 - (27)n ) / ( 33m x 23 ) = 1/27
    Apply the law of Fractional Exponents and Laws of Exponents
    (am)n = am x n ----------------1
    (am) x (an) = am + n-------------------2
    am ÷ an = am ? n----------------3
    and if pX = pY then X will be equal to Y. means X = Y;----------------4

    ⇒ ( 32n x 32 x 3n - 33n ) / ( 33m x 23 ) = 1/27
    Solve the equation.

    Correct Option: A

    ( 9n x 32 x (3-n/2)-2 - (27)n ) / ( 33m x 23 ) = 1/27
    ⇒ ( 32n x 32 x 3n - 33n) / ( 33m x 23 ) = 1/27
    ⇒ ( 32n + n x 32 - 33n) / ( 33m x 23 )= 1/27
    ⇒ ( 33n x 32 - 33n) / ( 33m x 23 ) = 1/27
    ⇒ 33n( 32 - 1) / ( 33m x 8 ) = 1/27
    ⇒ 33n( 9 - 1) / (33m x 8 ) = 1/27
    ⇒ ( 33n x 8 ) / (33m x 8 ) = 1/27
    ⇒ 33n / 33m = 1/27
    ⇒ 33n - 3m = 1/33
    ⇒ 33( n - m ) = 3-3
    3(n - m) = -3
    or n - m = -1
    or m - n = 1



  1. If x = √3 + 1/ √3 - 1 and y = √3 - 1/ √3 + 1, then x2 + y2 is equal to









  1. View Hint View Answer Discuss in Forum

    You can square the both the equation and add them to find the answer.

    x2 + y2 = ( (√3 + 1 ) / ( √3 - 1 ) )2 + ( (√3 - 1 ) / (√3 + 1) )2
    x2 + y2 = ( √3 + 1 )2 / ( √3 - 1 ) 2 + (√3 - 1 )2 / (√3 + 1) 2

    Solve further by applying the Law of Algebra formula

    Correct Option: A

    You can square the both the equation and add them to find the answer.

    x2 + y2 = ( (√3 + 1 ) / ( √3 - 1 ) )2 + ( (√3 - 1 ) / (√3 + 1) )2
    x2 + y2 = ( √3 + 1 )2 / ( √3 - 1 ) 2 + (√3 - 1 )2 / (√3 + 1) 2
    x2 + y2 = ( ( 3 + 1 + 2 √3 ) / ( 3 + 1 - 2 √3 ) ) + ( ( 3 + 1 - 2√3) / ( 3 + 1 + 2 √3 ) )
    x2 + y2 = ( 4 + 2 √3 ) / ( 4 - 2 √3 ) + ( 4 - 2√3 ) / ( 4 + 2 √3 )
    x2 + y2 = ( 2 + √3 ) / ( 2 - √3 ) + ( 2 - √3 ) / ( 2 + √3 )
    x2 + y2 = (4 + 3 + 4 √3 + 4 + 3 - 4 √3) / ( 4 - 3 )
    x2 + y2 = 14


  1. Find the quotient when (a-1 - 1) is divided by (a - 1).









  1. View Hint View Answer Discuss in Forum

    Given equation is
    a-1 - 1
    Apply the law of Fractional Exponents and Laws of Exponents
    x-y = 1/xy
    Rationalize the above equation and divide as per given question and solve it.

    Correct Option: D

    Given equation is
    a-1 - 1
    Apply the law of Fractional Exponents and Laws of Exponents
    x-y = 1/xy
    ⇒ a-1 - 1 = 1/a - 1
    ⇒ a-1 - 1 = (1 - a)/a
    Now divide by a - 1 in above equation,
    ⇒ ( a-1 - 1 ) ÷ (a - 1) = (1 - a)/a ÷ (a - 1)
    ⇒ ( a-1 - 1 ) ÷ (a - 1) = (1 - a)/a x 1/ (a - 1)
    ⇒ ( a-1 - 1 ) ÷ (a - 1) = -1x (a - 1)/a x 1/ (a - 1)
    ⇒ ( a-1 - 1 ) ÷ (a - 1) = -1/a
    ∴ Required quotient = -1/a.



  1. If 16 x 8n + 2 = 2m, then m is equal to









  1. View Hint View Answer Discuss in Forum

    Given that 16 x 8n + 2 = 2m

    Apply the law of Fractional Exponents and Laws of Exponents
    if a multiply three times a x a x a then
    a x a x a = a3
    if a multiply two times a x a then
    a x a = a2
    if a multiply n times a x a x a x....up to n times, then
    a x a x a x a ......up to n times = an
    and if pX = pY then X will be equal to Y. means X = Y;
    Law of exponent
    aman = am+n

    Correct Option: D

    Given that 16 x 8n + 2 = 2m

    Apply the law of Fractional Exponents and Laws of Exponents
    if a multiply three times a x a x a then
    a x a x a = a3
    if a multiply two times a x a then
    a x a = a2
    if a multiply n times a x a x a x....up to n times, then
    a x a x a x a ......up to n times = an
    ⇒ (2)4 x 23 x (n+2) = 2m
    ⇒ (2)4 x 23n+6 = 2m
    aman = am+n
    ⇒ (2)(4 + 3n + 6) = 2m
    ⇒ (2)(3n + 10) = 2m
    if pX = pY then X will be equal to Y. means X = Y;
    On comparing, we get
    3n + 10 = m
    ⇒ m = 3n + 10;