The sum of all real values of x satisfying the equation is: fr

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 Multiple Choice QuestionsMultiple Choice Questions

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1.

The sum of all real values of x satisfying the equation
left parenthesis straight x squared minus 5 straight x space plus 5 right parenthesis to the power of straight x squared plus 4 straight x minus 60 space equals space 1 end exponent is:

  • 3

  • -4

  • 6

  • 6


A.

3

Given, 

left parenthesis straight x squared minus 5 straight x space plus 5 right parenthesis to the power of straight x squared plus 4 straight x minus 60 end exponent space equals space 1
clearly comma space this space is space possible space when
straight I. space straight x squared space plus space 4 straight x minus 60 space equals space 0 space and space straight x squared minus 5 straight x space plus 5 space not equal to space 0
II. space straight x squared minus 5 straight x plus 5 space equals space 1
III. space straight x squared minus 5 straight x space plus 5 space equals space minus 1 space and space straight x squared plus 4 straight x minus 60 space equals space Even

Case space straight I space when space straight x squared space plus space 4 space straight x minus 60 space equals space 0 comma space then
straight x squared space plus space 10 space straight x space minus 6 straight x space minus 60 equals 0
rightwards double arrow space straight x left parenthesis straight x plus 10 right parenthesis minus 6 left parenthesis straight x plus 10 right parenthesis space equals space 0
rightwards double arrow left parenthesis straight x plus 10 right parenthesis left parenthesis straight x plus 6 right parenthesis space equals space 0
rightwards double arrow straight x space equals space minus space 10 space or space straight x equals space 6
Note space that comma space for space these space two space vaues space of space straight x comma space straight x squared minus 5 straight x space plus space 5 space not equal to 0
Case space II space when space straight x squared space minus 5 straight x space plus 5 space equals space 1
straight x squared space minus 5 straight x space plus 4 space equals space 0
straight x squared minus 4 straight x minus straight x space plus 4 equals 0
straight x left parenthesis straight x minus 4 right parenthesis minus 1 left parenthesis straight x minus 4 right parenthesis space equals 0
left parenthesis straight x minus 4 right parenthesis left parenthesis straight x minus 1 right parenthesis space equals 0
straight x equals space 4 space or space straight x space equals 1

Case space III space when space straight x squared minus 5 straight x space plus 5 space equals space minus 1
straight x squared minus 5 straight x space plus 5 space equals space minus 1
straight x squared minus 5 straight x space plus space 6 space equals space 0
rightwards double arrow space straight x squared minus 2 straight x minus 3 straight x space plus 6 space equals space 0
straight x left parenthesis straight x minus 2 right parenthesis minus 3 left parenthesis straight x minus 2 right parenthesis space equals space 0
left parenthesis straight x minus 2 right parenthesis left parenthesis straight x minus 3 right parenthesis space equals 0
straight x equals 2 space or space straight x space equals space 3
Now comma space when space straight x space equals space 2 comma space straight x to the power of 2 space end exponent plus 4 straight x minus 60 space equals space 4 plus 8 minus 60
equals negative 48 comma space which space is space an space interger
when space straight x space equals space 3 comma space straight x squared plus space 4 straight x space minus 60 space equals space 9 space plus 12 minus 60 space equals space minus 39
which space is space not space an space even space interger.
Thus comma space in space this space case comma space we space get space straight x space equals space 2
Hence comma space the space sum space of space all space real space values space of space
straight x space equals space minus 10 plus 6 plus 4 plus 1 plus 2 space equals 3

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2.

A complex number z is said to be unimodular, if |z|= 1. suppose z1 and z2 are complex numbers such that fraction numerator straight z subscript 1 minus 2 straight z subscript 2 over denominator 2 minus straight z subscript 1 begin display style stack straight z subscript 2 with minus on top end style end fraction is unimodular and z2 is not unimodular. Then, the point z1 lies on a

  • straight line parallel to X -axis

  • straight line parallel to Y -axis

  • circle of radius 2

  • circle of radius 2

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3.
Let α and  β be the roots of equations x2-6x-2 = 0. If ann- βn, for n≥1, the value of a10-2a8/2a9 is equal to 
  • 6

  • -6

  • 3

  • 3

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4.

The normal to the curve x2 + 2xy-3y2 =0 at (1,1)

  • does not meet the curve again

  • meets the curve again in the second quadrant

  • meets the curve again in the third quadrant

  • meets the curve again in the third quadrant

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5.

If z is a complex number such that |z|≥2, then the minimum value of open vertical bar straight z space plus space 1 half close vertical bar

  • is equal to 5/2

  • lies in the interval (1,2)

  • is strictly greater than 5/2

  • is strictly greater than 5/2

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6.

Let α and β be the roots of equation px2 +qx r =0 p ≠0. If p,q and r are in AP and 1 over straight alpha space plus space 1 over straight beta = 4, then the value of |α- β| is

  • fraction numerator square root of 61 over denominator 9 end fraction
  • fraction numerator 2 square root of 17 over denominator 9 end fraction
  • fraction numerator square root of 34 over denominator 9 end fraction
  • fraction numerator square root of 34 over denominator 9 end fraction
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7.

If the coefficients of x3 and x4 in the expansion of (1+ax+bx2)(1-2x)18 in powers of x are both zero, then (a,b) is equal to

  • open parentheses 16 comma 251 over 3 close parentheses
  • open parentheses 14 comma 251 over 3 close parentheses
  • open parentheses 14 comma 272 over 3 close parentheses
  • open parentheses 14 comma 272 over 3 close parentheses
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8.

If [a x b b x c c x a] = λ[a b c]2, then λ is equal to 

  • 0

  • 1

  • 2

  • 2

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9.

The real number k for which the equation, 2x3 +3x +k = 0 has two distinct real roots in [0,1]

  • lies between 1 and 2

  • lies between 2 and 3

  • lies between -1 and 0

  • lies between -1 and 0

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10.

If the equations x2 + 2x + 3 = 0 and ax2 + bx + c = 0, a, b, c ∈ R, have a common root, then a : b : c is

  • 1:2:3

  • 3:2:1

  • 1:3:2

  • 1:3:2

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