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Determinants

JEE Main 2026 (Online) 6th April Evening ShiftMCQMedium📈 Topic in 59% papers+4−1
Ques. 1JEE Main 2026, 6 April (Evening Shift)

The sum of all possible values of [0, 2 ], for which the system of equations : x 3 -8y-12z=0 x 2 +3y+3z=0 x+y+3z=0 has a non-trivial solution, is equal to :

  1. 2
  2. 3
  3. 4

Answer

(4) 4

Solution

For a non-trivial solution, the determinant of the coefficients must be zero:

vmatrix 3 & -8 & -12\ 2 & 3 & 3\ 1 & 1 & 3 vmatrix = 0

3 (9 - 3) + 8(3 2 - 3) - 12( 2 - 3) = 0

6 3 + 12 2 + 12 = 0

3 + 2 2 + 2 = 0

Putting c = : (4c3 - 3c ) + 2 (2c2 - 1 ) + 2 = 0

4c3 + 4c2 - 3c = 0 c(2c - 1)(2c + 3) = 0

So = 0 or = 12 ( = - 32 is not possible), and in [0, 2 ] this gives = 2, 3 2, 3, 5 3.

Sum = 2 + 2 = 4

Answer: (4)

Keep practising — Determinants

Ques. 2JEE Main 2026, 5 April (Morning Shift)

Let A be a 3 3 matrix such that AT bmatrix1\ 0\ 1 bmatrix= bmatrix5\ 2\ 2 bmatrix, AT bmatrix0\ 0\ 1 bmatrix= bmatrix3\ 1\ 1 bmatrix, A bmatrix1\ 0\ 1 bmatrix= bmatrix3\ 4\ 4 bmatrix and A bmatrix0\ 0\ 1 bmatrix= bmatrix1\ 3\ 1 bmatrix. If (A)=1, then (adj (A2+A ) ) is equal to:

  1. 16
  2. 25
  3. 49
  4. 64
Ques. 3JEE Main 2026, 5 April (Morning Shift)

Consider the system of linear equations in x, y, z : x+2y+tz=0 6x+y+5tz=0 3x+t2y+f(t)z=0 where f : R R is a differentiable function. If this system has infinitely many solutions for all t R, then f

  1. is a constant function
  2. is strictly increasing on R
  3. is strictly decreasing on R
  4. has two critical points
Ques. 4JEE Main 2026, 5 April (Evening Shift)

If f : N Z is defined by f(n)= vmatrixn & -1 & -5\ -2n2 & 3(2k+1) & 2k+1\ -3n3 & 3k(2k+1) & 3k(k+2)+1 vmatrix, k N, and n=1k f(n)=98, then k is equal to :

  1. 3
  2. 4
  3. 5
  4. 6
Ques. 5JEE Main 2026, 4 April (Morning Shift)

Let A= bmatrix1 & 1 & 2\ -2 & 0 & 1\ 1 & 3 & 5 bmatrix. Then the sum of all elements of the matrix adj (adj (2(adj A)-1 ) ) is equal to:

  1. 3
  2. 4
  3. -4
  4. -3
Ques. 6JEE Main 2026, 4 April (Evening Shift)

If the system of equations : x+y+z=5 x+2y+3z=9 x+3y+ z= has infinitely many solutions, then the value of + is :

  1. 16
  2. 18
  3. 19
  4. 21
Ques. 7JEE Main 2026, 4 April (Evening Shift)

Let A= bmatrix1 & 2 & 7\ 4 & -2 & 8\ 3 & 8 & -7 bmatrix and (A- I)=0, where is a real number. If the largest possible value of is p, then the circle (x-p)2+(y-2p)2=320, intersects the co-ordinate axes at

  1. 1 point
  2. 2 points
  3. 3 points
  4. 4 points
Ques. 8JEE Main 2026, 2 April (Morning Shift)

Let , R be such that the system of linear equations x+2y+z=5 2x+y+ z=5 8x+4y+ z=18 has no solution. Then is equal to :

  1. -4
  2. 4
  3. 8
  4. -8
Ques. 9JEE Main 2026, 2 April (Evening Shift)

If the system of equations x+5y+6z=4, 2x+3y+4z=7, x+6y+az=b has infinitely many solutions, then the point (a, b) lies on the line

  1. y-x=3
  2. x-y=3
  3. x+y=11
  4. x+y=12
Ques. 10JEE Main 2026, 24 January (Evening Shift)

Let P = [pij] and Q = [qij] be two square matrices of order 3 such that qij = 2(i+j-1)pij and (Q) = 210. Then the value of ( adj( adj P)) is:

  1. 81
  2. 16
  3. 124
  4. 32
Ques. 11JEE Main 2026, 24 January (Evening Shift)

Let f(x) = 7x10 + 9x8(1 + x2 + 2x9)2 dx, x > 0, x 0 f(x) = 0 and f(1) = 14. If A = bmatrix 0 & 0 & 1 \ 14 & f'(1) & 1 \ 2 & 4 & 1 bmatrix and B = adj(adj A) be such that |B| = 81, then 2 is equal to

  1. 2
  2. 4
  3. 3
  4. 1

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