Mathematics · Functions

JEE Main 2024 — 31 January, Shift 2 — Question 13

If the function f:(−∞,−1]→(a,b]\mathrm{f}:(-\infty,-1] \rightarrow(\mathrm{a}, \mathrm{b}] defined by f(x)=ex3−3x+1f(x)=e^{x^{3}-3 x+1} is one-one and onto, then the distance of the point P(2b+4,a+2)\mathrm{P}(2 b+4, a+2) from the line x+e−3y=4x+e^{-3} y=4 is :

  1. Option A:

    21+e62 \sqrt{1+\mathrm{e}^{6}}

    Correct
  2. Option B:

    41+e64 \sqrt{1+\mathrm{e}^{6}}

  3. Option C:

    31+e63 \sqrt{1+e^{6}}

  4. Option D:

    1+e6\sqrt{1+\mathrm{e}^{6}}

Answer: A

Step-by-step solution

f(x)=ex3−3x+1f(x)=e^{x^{3}-3 x+1}

f′(x)=ex3−3x+1⋅(3x2−3)f^{\prime}(x)=e^{x^{3}-3 x+1} \cdot\left(3 x^{2}-3\right)

=ex3−3x+1⋅3(x−1)(x+1)=\mathrm{e}^{\mathrm{x}^{3}-3 \mathrm{x}+1} \cdot 3(\mathrm{x}-1)(\mathrm{x}+1)

For f′(x)≥0\mathrm{f}^{\prime}(\mathrm{x}) \geq 0

∴f(x)\therefore \mathrm{f}(\mathrm{x}) is increasing function

∴a=e−∞=0=f(−∞)\therefore \mathrm{a}=\mathrm{e}^{-\infty}=0=\mathrm{f}(-\infty)

b=e−1+3+1=e3=f(−1)\mathrm{b}=\mathrm{e}^{-1+3+1}=\mathrm{e}^{3}=\mathrm{f}(-1)

P(2b+4,a+2)P(2 b+4, a+2)

∴P(2e3+4,2)\therefore \mathrm{P}\left(2 \mathrm{e}^{3}+4,2\right)

figure

d=(2e3+4)+2e−3−41+e−6=21+e6\mathrm{d}=\frac{\left(2 \mathrm{e}^{3}+4\right)+2 \mathrm{e}^{-3}-4}{\sqrt{1+\mathrm{e}^{-6}}}=2 \sqrt{1+\mathrm{e}^{6}}

Answer key and solution verified before publishing.

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Exam
JEE Main 2024
Subject
Mathematics
Chapter
Functions
Topic
One-One, many-one, onto, into, bijective functions
If the function f :(-∞,-1] rightarrow( a , b ] defined by f(x)=e x 3… | JEE Main 2024 PYQ with Solution · DhiX AI