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JEE Main
Exam
JEE Main
Subject
Mathematics
Chapter
Basics of Mathematics

JEE Main · Mathematics · Basics of Mathematics

Set of all real values of x satisfying the in equation _ 2 (x^ 2 -...

Set of all real values of xx satisfying the in equation log⁡2(x2−5x+4)log⁡2(x2+1)>1\dfrac{\log_{2}\left(x^{2} - 5x + 4\right)}{\log_{2}\left(x^{2} + 1\right)} > 1 is

Options

  1. A\left(- \infty , \dfrac{3}{5}\right) - \left\{0\right\}
  2. B\left(- \infty , 1\right) - \left\{0\right\}
  3. C(35,∞)\left(\dfrac{3}{5}, \infty\right)
  4. D(4,∞)\left(4, \infty\right)

Correct answer

A. \left(- \infty , \dfrac{3}{5}\right) - \left\{0\right\}

Step-by-step solution

Here, it is given that

log⁡2(x2−5x+4)log⁡2(x2+1)>1\dfrac{\log_{2}\left(x^{2} - 5x + 4\right)}{\log_{2} \left(x^{2} + 1\right)} > 1

x^{2} - 5x + 4 > 0 ⇒ \left(x - 4\right)\left(x - 1\right) > 0</p><p></p><p>⇒ x \in \left(- \infty ,1\right) \cup \left(4, \infty\right) . . . \left(1\right)</p><p></p><p>x^{2} + 1 > 0 whichistrue ~which is true~\forall x \in \mathbb{R} . . . \left(2\right)

log⁡2(x2−5x+4)>log⁡2(x2+1)\log_{2} \left(x^{2} - 5x + 4\right) > \log_{2} \left(x^{2} + 1\right)

x2−5x+4>x2+1x^{2} - 5x + 4 > x^{2} + 1

−5x+3>0- 5x + 3 > 0

x < \dfrac{3}{5} . . . \left(3\right)</p><p>Fromequations,(1),(2)</p><p>From equations, \left(1\right), \left(2\right) and \left(3\right)~we get

x \in \left(- \infty ,\dfrac{3}{5}\right) - \left\{0\right\}</p></p>

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