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Determinants

JEE Main 2024 (Online) 5th April Evening ShiftMCQEasy📈 Topic in 59% papers+4−1
Ques. 1JEE Main 2024, 5 April (Evening Shift)

The values of m, n, for which the system of equations x + y + z = 4, 2x + 5y + 5z = 17, x + 2y + mz = n has infinitely many solutions, satisfy the equation :

  1. m2 + n2 - m - n = 46
  2. m2 + n2 + mn = 68
  3. m2 + n2 - mn = 39
  4. m2 + n2 + m + n = 64

Answer

(3) m2 + n2 - mn = 39

Solution

Infinitely many solutions = 0 and 1 = 2 = 3 = 0

= vmatrix 1 & 1 & 1 \ 2 & 5 & 5 \ 1 & 2 & m vmatrix = 3m - 6 = 0 m = 2

3 = vmatrix 1 & 1 & 4 \ 2 & 5 & 17 \ 1 & 2 & n vmatrix = 3n - 21 = 0 n = 7

(With m = 2, n = 7: 1 = 0 (two equal columns) and 2 = 0.)

m2 + n2 - mn = 4 + 49 - 14 = 39

Answer: (3)

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Ques. 2JEE Main 2024, 5 April (Evening Shift)

Let 0 and A = bmatrix & & 3 \ & & \ - & & 2 bmatrix. If B = bmatrix 3 & -9 & 3 \ - & 7 & -2 \ -2 & 5 & -2 bmatrix is the matrix of cofactors of the elements of A, then (AB) is equal to :

  1. 64
  2. 343
  3. 125
  4. 216
Ques. 3JEE Main 2024, 4 April (Morning Shift)

Let (0, ) and A= bmatrix1 & 2 & \ 1 & 0 & 1 \ 0 & 1 & 2 bmatrix. If det ( adj (2A-AT ) adj (A-2AT ) )=28, then ( det(A))2 is equal to:

  1. 16
  2. 36
  3. 49
  4. 1
Ques. 4JEE Main 2024, 4 April (Morning Shift)

If the system of equations x+( 2 )y+( 2 )z=0 x+( )y+( )z=0 x+( )y-( )z=0 has a non-trivial solution, then (0, 2 ) is equal to :

  1. 5 24
  2. 11 24
  3. 7 24
  4. 3 4
Ques. 5JEE Main 2024, 4 April (Morning Shift)

Let A be a 3 3 matrix of non-negative real elements such that A bmatrix1\\1\\1 bmatrix=3 bmatrix1\\1\\1 bmatrix. Then the maximum value of (A) is .

Ques. 6JEE Main 2024, 1 February (Morning Shift)

If A= bmatrix 2 & 1\ -1 & 2 bmatrix, B= bmatrix1 & 0\ 1 & 1 bmatrix, C=ABAT and X=ATC2A, then is equal to :

  1. 243
  2. 729
  3. 27
  4. 891
Ques. 7JEE Main 2024, 1 February (Morning Shift)

If the system of equations 2x+3y-z=5 x+ y+3z=-4 3x-y+ z=7 has infinitely many solutions, then 13 is equal to :

  1. 1110
  2. 1120
  3. 1210
  4. 1220
Ques. 8JEE Main 2024, 1 February (Evening Shift)

Let the system of equations x+2 y+3 z=5, 2 x+3 y+z=9, 4 x+3 y+ z= have infinite number of solutions. Then +2 is equal to :

  1. 22
  2. 17
  3. 15
  4. 28
Ques. 9JEE Main 2024, 31 January (Morning Shift)

If the system of linear equations x-2y+z=-4 2x+ y+3z=5 3x-y+ z=3 has infinitely many solutions, then 12 +13 is equal to

  1. 60
  2. 54
  3. 64
  4. 58
Ques. 10JEE Main 2024, 31 January (Morning Shift)

If f(x)= vmatrix x3 & 2x2+1 & 1+3x \ 3x2+2 & 2x & x3+6 \ x3-x & 4 & x2-2 vmatrix for all x R, then 2f(0)+f'(0) is equal to

  1. 24
  2. 18
  3. 42
  4. 48
Ques. 11JEE Main 2024, 31 January (Evening Shift)

Let A be a 3 3 real matrix such that A pmatrix1\\0\\1 pmatrix=2 pmatrix1\\0\\1 pmatrix, A pmatrix-1\\0\\1 pmatrix=4 pmatrix-1\\0\\1 pmatrix, A pmatrix0\\1\\0 pmatrix=2 pmatrix0\\1\\0 pmatrix. Then, the system (A-3I) pmatrixx\ \ pmatrix= pmatrix1\\2\\3 pmatrix has :

  1. exactly two solutions
  2. infinitely many solutions
  3. unique solution
  4. no solution

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