Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 202311 AprilMorning Shift
Exam
JEE Main
Year
2023
Date
11 April
Shift
Morning Shift
Subject
Mathematics
Chapter
Basics of Mathematics

JEE Main 2023 · 11 April · Morning Shift · Mathematics · Basics of Mathematics

The number of integral solution x of _ (x + (7)/(2)) ((x - 7)/(2x -...

The number of integral solution xx of log⁡(x+72)(x−72x−3)2≥0\log_{\left(x + \dfrac{7}{2}\right)}{\left(\dfrac{x - 7}{2x - 3}\right)}^{2} \ge 0 isThe number of integral solution x of _ (x + (7)/(2)) ((x - 7)/(2x - 3)) ^ 2 ≥ 0 isThe number of integral solution x of _ (x + (7)/(2)) ((x - 7)/(2x - 3)) ^ 2 ≥ 0 is

Options

  1. A77
  2. B88
  3. C66
  4. D55

Correct answer

C. 66

Step-by-step solution

We have been given thatlog⁡(x+72)(x−72x−3)2≥0\log_{\left(x + \dfrac{7}{2}\right)}{\left(\dfrac{x - 7}{2x - 3}\right)}^{2} \ge 0

We need to find the domain.

For log⁡g(x)(f(x))\log_{g\left(x\right)}\left(f\left(x\right)\right) is defined when f(x)>0f\left(x\right) > 0 and g(x)>0,g(x)≠1g\left(x\right) > 0, g\left(x\right) \ne 1.

⇒x+72>0⇒ x + \dfrac{7}{2} > 0

⇒x>−72⇒ x > \dfrac{- 7}{2}

Also, x+72≠1x + \dfrac{7}{2} \ne 1

⇒x≠−52⇒ x \ne \dfrac{- 5}{2}

And x−72x−3≠0\dfrac{x - 7}{2x - 3} \ne 0

⇒x≠7⇒ x \ne 7 and x≠32x \ne \dfrac{3}{2}

Domain : \left(- \dfrac{7}{2}, \infty\right) - \left\{\dfrac{- 5}{2}, 0, \dfrac{3}{2}\right\}</p><p>Nowletustakedifferentcases.</p><p>CaseI:</p><p>Now let us take different cases.</p><p>Case I:0 < x + \dfrac{7}{2} < 1<br/><br />⇒ - \dfrac{7}{2} < x < - \dfrac{5}{2} . . . . . ( 1 )</p><p></p><p>⇒ {\left(\dfrac{x - 7}{2x - 3}\right)}^{2} \le 1</p><p></p><p>⇒ - 1 \le \dfrac{x - 7}{2x - 3} \le 1</p><p></p><p>⇒ \dfrac{x - 7}{2x - 3} + 1 \ge 0</p><p></p><p>⇒ \dfrac{x - 7 + 2x - 3}{2x - 3} \ge 0</p><p></p><p>⇒ \dfrac{3x - 10}{2x - 3} \ge 0 . . . ( 2 )</p><p><imgsrc="https://cdn−question−pool.getmarks.app/pyq/jeemain/f30cb77d−6d61−4df2−9dae−21d79ad0e070−image.png"style="width:200px;height:108px;"/></p><p>And</p><p><img src="https://cdn-question-pool.Quantrex.app/pyq/jee_main/f30cb77d-6d61-4df2-9dae-21d79ad0e070-image.png" style="width: 200px; height: 108px;" /></p><p>And\dfrac{x - 7}{2x - 3} - 1 \le 0</p><p></p><p>⇒ \dfrac{x - 7 - 2x + 3}{2x - 3} \le 0</p><p></p><p>⇒ \dfrac{- x - 4}{2x - 3} \le 0</p><p></p><p>⇒ \dfrac{x + 4}{2x - 3} \ge 0 . . . . ( 3 )</p><p><imgsrc="https://cdn−question−pool.getmarks.app/pyq/jeemain/13daeaf2−89a8−49a3−8a01−d61a28251a39−image.png"style="width:200px;height:95px;"/></p><p>From</p><p><img src="https://cdn-question-pool.Quantrex.app/pyq/jee_main/13daeaf2-89a8-49a3-8a01-d61a28251a39-image.png" style="width: 200px; height: 95px;" /></p><p>From\left(1\right), (2),\left(2\right),\left(3\right)wecantellthatthereisnointersection,nosolution</p><p>CaseII:</p><p>we can tell that there is no intersection, no solution</p><p>Case II:</p><p>⇒ x + \dfrac{7}{2} > 1</p><p></p><p>⇒ x > - \dfrac{5}{2}</p><p></p><p>⇒ {\left(\dfrac{x - 7}{2x - 3}\right)}^{2} \ge 1</p><p></p><p>⇒ \left|\dfrac{x - 7}{2x - 3}\right| \ge 1</p><p></p><p>⇒ \dfrac{x - 7}{2x - 3} \le - 1</p><p></p><p>⇒ x \in \left(\dfrac{3}{2}, \dfrac{10}{3}\right]</p><p>Or,</p><p>Or,\dfrac{x - 7}{2x - 3} \ge 1</p><p></p><p>⇒ \dfrac{x - 7 - 2x + 3}{2x - 3} \ge 0</p><p></p><p>⇒ \dfrac{x + 4}{2x - 3} \le 0</p><p></p><p>⇒ x \in \left[- 4, \dfrac{3}{2}\right)</p><p></p><p>x \in \left(- \dfrac{5}{2}, \dfrac{3}{2}\right) \cup \left(\dfrac{3}{2}, \dfrac{10}{3}\right]</p><p>Hencetherearetotal6integers{−2,−1,0,1,2,3}</p><p>Hence there are total 6 integers \left\{- 2, - 1, 0, 1, 2, 3\right\}.

Hence this is the required option.

Practice Basics of Mathematics on Quantrex Academy →

More from Basics of Mathematics

All Basics of Mathematics questions Full Basics of Mathematics list Basics of Mathematics JEE Maths PYQsJEE Mathematics PYQs All JEE Main PYQs