The solution of the equation log101log7x + 7 

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

The number of solution(s) of the equation x + 1 - x - 1 = 4x - 1 is/are

  • 2

  • 0

  • 3

  • 1


2.

The value of z2 + z - 32 + z - i2 is minimum when z equals

  • 2 - 23i

  • 45 + 3i

  • 1 + i3

  • 1 - i3


3.

If limx02asinx - sin2xtan3x exists and is equal to 1, then the value of α is

  • 2

  • 1

  • 0

  • - 1


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4.

The solution of the equation log101log7x + 7 + x = 0 is

  • 3

  • 7

  • 9

  • 49


C.

9

Given, log101log7x + 7 + x = 0

 log7x + 7 + x = 1000 log7x + 7 + x = 1 x + 7 + x = 71 x + 7 + x = 7On squaring both sides, we getx + 7 + x + 2x2 + 7x = 49 2x - 42 = - 2x2 + 7x x - 21 = - x2 + 7x

Again, squaring both sides, we get

x2 + 441 - 42x = x + 7x

 49x = 441     x = 44149     x = 9


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5.

The number of digits in 20301 given, log102 = 0.3010 is

  • 602

  • 301

  • 392

  • 391


6.

If R be the set of all real numbers and f : R ➔ R is given by f(x) = 3x2 + 1. Then, the set f-1([1, 6]) is

  • - 53, 0, 53

  • - 53,  53

  • - 13, 13

  •  - 53, 53


7.

The value of tanπ2 + 2tan2π5 + 4cot4π5 is

  • cotπ5

  • cot2π5

  • cot4π5

  • cot3π5


8.

Let the number of elements of the sets A and B be p and q, respectively. Then, the number of relations from the set A to the set B is

  • 2p + q

  • 2pq

  • p + q

  • pq


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9.

In a ABCtanA and tanB are the roots of pq(x2 + 1) = r2x. Then, ABC is

  • a right angled triangle

  • an acute angled triangle

  • an obtuse angled triangle

  • an equilateral triangle


10.

If y = 4x + 3 is parallel to a tangent to the parabola y2 = 12x, then its distance from the normal parallel to the given line is

  • 21317

  • 21917

  • 21117

  • 21017


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