Define a relation R on A = {1, 2, 3, 4} as xRy if x divides y. R

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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1.

Define a relation R on A = {1, 2, 3, 4} as xRy if x divides y. R is

  • reflexive and transitive

  • reflexive and symmetric

  • symmetric and transitive

  • equivalence


A.

reflexive and transitive

Given set A= 1, 2, 3, 4 and relation, xRy if x divides y. Relation = 1, 1, 2, 2, 3, 3, 4, 4, 1, 2, 1, 3, 1, 4, 2, 4Reflexive : We have, xRy  y/x for x, y  AFor any x  A, we have x/x  xRx.Thus, xRx for all x  A. So, R is reflexive on A.Symmetry : R ia not symmetry because,if y/x, then x may not divide y.For example 4/2 but 2/4.Transitive : Let x, y, z  A, such that xRy and yRz.Then, xRy and yRz  yx and zy  zx.So, R is a transitive relation on A.

Hence, option(a) reflexive and transitive is correct.


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2.

If lines represented by x + 3y - 6 = 0, 2x + y - 4 = 0 and kx - 3y + 1 = 0 are concurrent, then the value of k is

  • 619

  • 196

  • - 196

  • - 619


3.

If f(x) = fx = logxx - 1, if x  1k,          if x  1 is continuous at x = 1, then the value of k is

  • 0

  • - 1

  • 1

  • e


4.

If A = cosθsinθ- sinθcosθ, then A . A' is

  • I

  • A

  • - A

  • A2


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5.

If 12- 11x - 21x11 is singular, then the value of x is

  • 2

  • 3

  • 1

  • 0


6.

If A and B are symmetric matrices of the same order, then which one of the following is not true ?

  • A + B is symmetric

  • A - B is symmetric

  • AB + BA is symmetric

  • AB - BA is symmetric


7.

If w is an imaginary cube root of unity, then the value 1w21 - w4w11 + w51ww2 is

  • - 4

  • w2 - 4

  • w2

  • 4


8.

On the set of all non-zero reals, an operation * is defined as a * b = 3ab2. In this group, a solution of (2 * x) * 3-1 = 4-1 is

  • 6

  • 1

  • 1/6

  • 3/2


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9.

G = xxxx, x is a non-zero real number is a roup with respect to matrix multiplication. In this group, the inverse of 13131313 is

  • 43434343

  • 34343434

  • 3333

  • 1111


10.

The domain of f(x) = sin-1log2x2 is

  • 0  x  1

  • 0  x  4

  • 1  x  4

  • 4  x  6


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