If m is the AMN of two distinct real numbers l and n (l,n>1)

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

Let A and B be two sets containing four and two elements respectively. Then the number of subsets of the set A x B, each having at least three elements is:

  • 219

  • 256

  • 275

  • 275

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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

264 Views

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

856 Views

4.

The number of integers greater than 6000 that can be formed, using the digits 3,5,6,7 and 8 without repetition, is

  • 216

  • 192

  • 120

  • 120

358 Views

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5.

The sum of coefficients of integral powers of x in the binomial expansion of left parenthesis 1 minus 2 square root of straight x right parenthesis to the power of 50 space is

  • 1 half left parenthesis 3 to the power of 50 space plus space 1 right parenthesis
  • 1 half left parenthesis 30 to the power of 50 right parenthesis
  • 1 half left parenthesis 30 to the power of 50 minus 1 right parenthesis
  • 1 half left parenthesis 30 to the power of 50 minus 1 right parenthesis
360 Views

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6.

If m is the AMN of two distinct real numbers l and n (l,n>1) and G1, G2, and G3 are three geometric means between l and n, then straight G subscript 1 superscript 4 space plus 2 straight G subscript 2 superscript 4 space plus space straight G subscript 3 superscript 4 equals

  • 4l2 mn

  • 4lm2n

  • 4 lmn2

  • 4 lmn2


B.

4lm2n

Given, 
m is the AM of and n

l +n = 2m

and G1, G2, G3, n are in GP
Let r be the common ratio of this GP
G1 = lr
G2 =lr2
G3= lr3
n = lr4

rightwards double arrow space straight r space equals space open parentheses straight n over l close parentheses to the power of 1 divided by 4 end exponent
Now comma space straight G subscript 1 superscript 4 space plus space 2 straight G subscript 2 superscript 4 space plus space straight G subscript 3 superscript 4 space equals left parenthesis l straight r right parenthesis to the power of 4 space plus space left parenthesis l straight r squared right parenthesis to the power of 4 space plus space left parenthesis l straight r cubed right parenthesis to the power of 4
space equals space straight l to the power of 4 space straight x space straight r to the power of 4 left parenthesis 1 plus 2 straight r to the power of 4 plus straight r to the power of 8 right parenthesis
equals space straight l to the power of 4 space straight x space straight r to the power of 4 space left parenthesis straight r to the power of 4 space plus 1 right parenthesis squared
equals space straight l to the power of 4 space straight x space straight n over straight l open parentheses fraction numerator n italic plus italic 1 over denominator l end fraction close parentheses
equals space l n italic space x italic 4 m to the power of italic 2 italic space italic equals italic space italic 4 l m to the power of italic 2 n

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7.

The sum of first 9 terms of the series 1 cubed over 1 space plus fraction numerator 1 cubed plus 2 cubed over denominator 1 plus 3 end fraction space plus space fraction numerator 1 cubed plus 2 cubed plus 3 cubed over denominator 1 plus 2 plus 3 end fraction space.... is

  • 71

  • 96

  • 142

  • 142

194 Views

8.

The negation of tilde space straight s space logical or left parenthesis tilde straight r logical and straight s right parenthesis is equivalent to

  • straight s logical and tilde straight r
  • straight s logical and left parenthesis straight r logical and tilde straight s right parenthesis
  • straight s logical or left parenthesis straight r space straight v tilde straight s right parenthesis
  • straight s logical or left parenthesis straight r space straight v tilde straight s right parenthesis
303 Views

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9.

If the angles of elevation of the top of a tower from three collinear points A, B and C on line leading to the foot of the tower are 30o, 45o and 60o respectively, then the ratio AB: BC is 

  • square root of 3 space colon space 1
  • square root of 3 space colon space square root of 2
  • 1 colon square root of 3
  • 1 colon square root of 3
251 Views

10.

The mean of the data set comprising of 16 observations is 16. If one of the observation value 16 is deleted and three new observations valued3,4 and 5 are added to the data, then the mean of the resultant data is

  • 16.8

  • 16.0

  • 15.8

  • 15.8

449 Views

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