If A, then adj (3A2 + 12A) is equal to from Mathematics Determi

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 Multiple Choice QuestionsMultiple Choice Questions

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11.

If A, open square brackets table row 2 cell negative 3 end cell row cell negative 4 end cell 1 end table close square bracketsthen adj (3A2 + 12A) is equal to

  • open square brackets table row 72 cell negative 63 end cell row cell negative 84 end cell 51 end table close square brackets
  • open square brackets table row 72 cell negative 84 end cell row cell negative 63 end cell 51 end table close square brackets
  • open square brackets table row 51 63 row 84 72 end table close square brackets
  • open square brackets table row 51 63 row 84 72 end table close square brackets


C.

open square brackets table row 51 63 row 84 72 end table close square brackets
Given space straight A space equals space open square brackets table row 2 cell negative 3 end cell row cell negative 4 end cell 1 end table close square brackets
3 straight A squared space equals space open square brackets table row 16 cell negative 9 end cell row cell negative 12 end cell 13 end table close square brackets
12 space straight A space equals space open square brackets table row 24 cell negative 36 end cell row cell negative 48 end cell 12 end table close square brackets
therefore space 3 straight A squared space plus space 12 space straight A space equals space open square brackets table row 72 cell negative 63 end cell row cell negative 84 end cell 51 end table close square brackets
adj space left parenthesis 3 straight A squared space plus space 12 space straight A right parenthesis space equals space open square brackets table row 51 63 row 84 72 end table close square brackets
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12.

Let A be a 2 × 2 matrix with real entries. Let I be the 2 × 2 identity matrix. Denote by tr (A), the sum of diagonal entries of A. Assume that A2= I.
Statement −1: If A ≠ I and A ≠ − I, then det A = − 1.
Statement −2: If A ≠ I and A ≠ − I, then tr (A) ≠ 0.

  • Statement −1 is false, Statement −2 is true

  • Statement −1 is true, Statement −2 is true, Statement −2 is a correct explanation for Statement −1

  • Statement −1 is true, Statement −2 is true; Statement −2 is not a correct explanation for Statement −1.

  • Statement −1 is true, Statement −2 is true; Statement −2 is not a correct explanation for Statement −1.

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13.

Let A be a square matrix all of whose entries are integers. Then which one of the following is true?

  • If det A = ± 1, then A–1 exists but all its entries are not necessarily integers

  • If detA ≠ ± 1, then A–1 exists and all its entries are non-integers

  • If detA = ± 1, then A–1 exists and all its entries are integers

  • If detA = ± 1, then A–1 exists and all its entries are integers

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14.

Let a, b, c be any real numbers. Suppose that there are real numbers x, y, z not all zero such that x = cy + bz, y = az + cx and z = bx + ay. Then a2 + b2 + c2 + 2abc is equal to

  • 2

  • -1

  • 0

  • 0

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15.

If D = open vertical bar table row 1 1 1 row 1 cell 1 plus straight x end cell 1 row 1 1 cell 1 plus straight y end cell end table close vertical barfor x ≠ 0, y ≠ 0 then D is

  • divisible by neither x nor y

  • divisible by both x and y

  • divisible by x but not y

  • divisible by x but not y

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16.

Let A =  open square brackets table row 5 cell 5 straight alpha end cell straight alpha row 0 straight alpha cell 5 straight alpha end cell row 0 0 5 end table close square brackets  If |A2| = 25, then |α| equals

  • 52

  • 1

  • 1/5

  • 1/5

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17.

Let straight A space equals space open parentheses table row 1 2 row 3 4 end table close parentheses space and space straight B space equals open parentheses table row straight a 0 row 0 straight b end table close parentheses a , b ∈ N. Then

  • there cannot exist any B such that AB = BA

  • there exist more than one but finite number of B’s such that AB = BA

  • there exists exactly one B such that AB = BA

  • there exists exactly one B such that AB = BA

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18.

If a1, a2, a3,…, an,… are in G.P., then the determinant

space increment space equals space open vertical bar table row cell log space straight a subscript straight n end cell cell log space straight a subscript straight n plus 1 end subscript end cell cell log space straight a subscript straight n plus 2 end subscript end cell row cell log space straight a subscript straight n plus 3 end subscript end cell cell log space straight a subscript straight n plus 4 end subscript end cell cell log space straight a subscript straight n plus 5 end subscript end cell row cell log space straight a subscript straight n plus 6 end subscript end cell cell log space straight a subscript straight n plus 7 end subscript end cell cell log space straight a subscript straight n plus 8 end subscript end cell end table close vertical bar space is space equal space to

  • 1

  • 0

  • 4

  • 4

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19.

If the system of linear equations
x + ky + 3z = 0
3x + ky – 2z = 0
2x + 4y – 3z = 0

has a non-zero solution (x,y,z), then xz/y2 is equal to

  • 30

  • -10

  • 10

  • -30


20.

If x-42x2x2xx-42x2x2xx-4 = (A +Bx)(x-A)2, then the ordered pair (A,B) is equal to

  • (4,5)

  • (-4,-5)

  • (-4,3)

  • (-4,5)


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