Mathematics · Limits, Continuity and Differentiability

JEE Main 2026 — 6 April, Evening Shift — Question 35

Let lim⁡x→2(tan⁡(x−2))(rx2+(p−2)x−2p)(x−2)2=5\lim_{x\to 2}\frac{(\tan(x-2))(rx^{2} + (p-2)x - 2p)}{(x-2)^{2}} = 5 for some r,p∈R.r,p∈R. If the set of all possible values of qq such that the roots of the equation rx2−px+q=0rx^{2} - px + q = 0 lie in (0,2),(0,2), be the interval (α,β],(α,β], then 4(α+β)4(α+β) equals:

  1. Option A:

    11

  2. Option B:

    13

  3. Option C:

    17

    Correct
  4. Option D:

    21

Answer: C

Step-by-step solution

lim⁡x→2tan⁡(x−2)x−2⋅[rx2+(p−2)x−2p]x−2=5\lim _{\mathrm{x} \rightarrow 2} \frac{\tan (\mathrm{x}-2)}{\mathrm{x}-2} \cdot \frac{\left[\mathrm{rx}^{2}+(\mathrm{p}-2) \mathrm{x}-2 \mathrm{p}\right]}{\mathrm{x}-2}=5 ⇒lim⁡x→2rx2−2x+p(x−2)x−2=5\Rightarrow \lim _{\mathrm{x} \rightarrow 2} \frac{\mathrm{rx}^{2}-2 \mathrm{x}+\mathrm{p}(\mathrm{x}-2)}{\mathrm{x}-2}=5 ∵Dr→0∴ Nr→0⇒r=1\because \mathrm{D}^{\mathrm{r}} \rightarrow 0 \therefore \mathrm{~N}^{\mathrm{r}} \rightarrow 0 \Rightarrow \mathrm{r}=1 ⇒lim⁡x→2x(x−2)+p(x−2)x−2=5\Rightarrow \lim _{\mathrm{x} \rightarrow 2} \frac{\mathrm{x}(\mathrm{x}-2)+\mathrm{p}(\mathrm{x}-2)}{\mathrm{x}-2}=5 ⇒2+p=5\Rightarrow 2+\mathrm{p}=5 ⇒p=3\Rightarrow \mathrm{p}=3 Now, quadratic equation is x2−3x+q=0\mathrm{x}^{2}-3 \mathrm{x}+\mathrm{q}=0 its both roots lie in (0,2)(0,2) D≥0,0<−b2a<2,f(0)>0,f(2)>0\mathrm{D} \geq 0, 0<\frac{-\mathrm{b}}{2 \mathrm{a}}<2, \mathrm{f}(0)>0, \mathrm{f}(2)>0 ⇒9−4q≥0\Rightarrow 9-4 \mathrm{q} \geq 0 and q>2\mathrm{q}>2 ⇒q∈(2,94]\Rightarrow \mathrm{q} \in\left(2, \frac{9}{4}\right] α=2,β=94⇒(2+94)=17\alpha=2, \beta=\frac{9}{4} \Rightarrow\left(2+\frac{9}{4}\right)=17

Solution figure

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Limits, Continuity and Differentiability
Topic
Introduction to Limit
Let lim xto 2 frac (tan(x-2))(rx 2 + (p-2)x - 2p) (x-2) 2 = 5 for… | JEE Main 2026 PYQ with Solution · DhiX AI