Mathematics · Functions

JEE Main 2026 — 22 January, Evening Shift — Question 14

Let the domain of the function f(x)=log⁡3log⁡5(7−log⁡2(x2−10x+85))+sin⁡−1(∣3x−717−x∣)\mathrm{f}(\mathrm{x})=\log _{3} \log _{5}\left(7-\log _{2}\left(\mathrm{x}^{2}-10 \mathrm{x}+85\right)\right)+\sin ^{-1}\left(\left|\frac{3 \mathrm{x}-7}{17-\mathrm{x}}\right|\right) be (α,β](\alpha, \beta]. Then α+β\alpha+\beta is equal to :

  1. Option A:

    1010

  2. Option B:

    1212

  3. Option C:

    99

    Correct
  4. Option D:

    88

Answer: C

Step-by-step solution

Let x2−10x+85=λ\mathrm{x}^{2}-10 \mathrm{x}+85=\lambda

∴ Domain for first term λ>0\begin{gathered} \lambda>0 \end{gathered}  7−log⁡2λ>0⇒λ<27\begin{gathered} \ 7-\log _{2} \lambda>0 \Rightarrow \lambda<2^{7} \end{gathered}  log⁡5(7−log⁡2λ)>0⇒λ<26\begin{gathered} \ \log _{5}\left(7-\log _{2} \lambda\right)>0 \Rightarrow \lambda<2^{6} \end{gathered}

∴ from (1), 0<λ<260<\lambda<2^{6}

0<x2−10x+85<640<\mathrm{x}^{2}-10 \mathrm{x}+85<64 ⇒x∈(3,7)\begin{gathered} \Rightarrow \mathrm{x} \in(3,7) \end{gathered}

domain for second term −1≤3x−7x−17≤1-1 \leq \frac{3 x-7}{x-17} \leq 1

⇒x∈[−5,6]\begin{gathered} \Rightarrow \mathrm{x} \in[-5,6] \end{gathered}

From (A) & (B),

domain of function will be ( 3,6 ]

⇒α=3,β=6\Rightarrow \alpha=3, \beta=6

⇒α+β=9\Rightarrow \alpha+\beta=9

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Subject
Mathematics
Chapter
Functions
Topic
Domain & range of functions
Let the domain of the function f ( x )=log 3 log 5 (7-log 2 ( x 2 -10… | JEE Main 2026 PYQ with Solution · DhiX AI