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Determinants

JEE Main 2024 (Online) 4th April Morning ShiftNumericalMedium📈 Topic in 7% papers+4
Ques. 1JEE 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 .

Answer

27

Solution

Let rows of A be (a1, a2, a3), (b1, b2, b3), (c1, c2, c3), all elements 0

Given equation each row sum =3:

a1+a2+a3=b1+b2+b3=c1+c2+c3=3

(A)=(a1b2c3+a2b3c1+a3b1c2)

-(a3b2c1+a2b1c3+a1b3c2)

a1b2c3+a2b3c1+a3b1c2 ( the subtracted terms are 0)

(a1+a2+a3)(b1+b2+b3)(c1+c2+c3)=27

( this product contains these three terms plus other non-negative terms)

Equality for A=3I, (A)=27

Answer: 27

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Ques. 2JEE 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. 3JEE 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. 4JEE 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. 5JEE 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. 6JEE 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. 7JEE 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
Ques. 8JEE Main 2024, 31 January (Evening Shift)

Let A be a 3 3 matrix and (A)=2. If n= ( 2024 times adj(adj( (adj A)))), then the remainder when n is divided by 9 is equal to .

Ques. 9JEE Main 2024, 30 January (Morning Shift)

If f(x)= vmatrix2 4x & 2 4x & 3+ 2 2x\ 3+2 4x & 2 4x & 2 2x\ 2 4x & 3+2 4x & 2 2x vmatrix, then 15f'(0) is equal to :

  1. 2
  2. 1
  3. 0
  4. 6
Ques. 10JEE Main 2024, 30 January (Morning Shift)

Consider the system of linear equations x+y+z=4 , x+2y+2 z=10 , x+3y+4 2z= 2+15 where , . Which one of the following statements is NOT correct ?

  1. The system has unique solution if 12 and 1, 15
  2. The system has infinite number of solutions if = 12 and =15
  3. The system is consistent if 12
  4. The system is inconsistent if = 12 and 1
Ques. 11JEE Main 2024, 30 January (Evening Shift)

Let R= pmatrixx&0&0\\0&y&0\\0&0&z pmatrix be a non-zero 3 3 matrix, where x =y ( + 2 3 )=z ( + 4 3 ) 0, (0,2 ). For a square matrix M, let trace (M) denote the sum of all the diagonal entries of M. Then, among the statements: (I) Trace (R)=0 (II) If trace (adj(adj(R)))=0, then R has exactly one non-zero entry.

  1. Only (I) is true
  2. Only (II) is true
  3. Both (I) and (II) are true
  4. Neither (I) nor (II) is true

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