CTET Solved Paper - UPTET Feburary 2014 Paper2

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116. If (x - 2) is a factor of x3 + ax2 + bx + 16 and b = 4a, then respective values of a and b are

  • Option : C
  • Explanation : Let f (x) = x3 + ax2 + bx + 16
    Since, (x - 2) is a factor of f (x)
    ∴ f (2) = 0
    i.e. 8 + 4a + 2b + 16 = 0
    ⇒ 8 + 4a + 8a + 16 = 0 [as b = 4a]
    ∴ a = -2
    and b = 4a-8
    ⇒ b=4(-2)=-8
    ⇒ a = -2, b = -8.
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117. If the area of an equilateral triangle is 16√3 cm2, then the perimeter of the triangle is

  • Option : B
  • Explanation : Let side of equilateral triangle = a cm.
    ∴ √3/4 a2 = 16√3
    ⇒ a = 8cm.
    ∴ Perimeter = 3a = 24cm.
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118. Mode of the given data 29, 25,38,22,38, 25, 38, 29 is

  • Option : B
  • Explanation : 38 is the observation with the maximum frequency. .'. Mode is 38.
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119. The polynomial P (x) = x4 - 2x3 + 3x2 - ax + 3a - 7 when divided by (x + 1) leaves the remainder 19. The value of a is

  • Option : C
  • Explanation : P (x) = (x + 1)· g (x) + 19,
    where g(x) is the quotient
    ⇒ P (x) - 19 = (x+l)· g (x)
    i.e. (x+l) divides P (x) - 19 completely.
    i.e. P (-1) - 19 = 0
    (-1)4 - 2(-1)3 + 3(-1)2 - a (-1) + 3a - 7 + 19 = 0
    1 + 2 + 3 + a + 3a - 7 -19 = 0
    ⇒ 4a = 20
    ⇒ a = 5.
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