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JEE Main 202628 JanuaryEvening Shift
Exam
JEE Main
Year
2026
Date
28 January
Shift
Evening Shift
Subject
Mathematics
Chapter
Functions

JEE Main 2026 · 28 January · Evening Shift · Mathematics · Functions

Given below are two statements: Statement I: The function f: R...

Given below are two statements: Statement I: The function f:R→Rf: \mathbf{R} \rightarrow \mathbf{R} defined by f(x)=x1+∣x∣f(x)=\frac{x}{1+|x|} is one-one. Statement II: The function f:R→Rf: \mathbf{R} \rightarrow \mathbf{R} defined by f(x)=x2+4x−30x2−8x+18f(x)=\frac{x^{2}+4 x-30}{x^{2}-8 x+18} is many-one.
In the light of the above statements, choose the correct answer from the options given below :

Options

  1. ABoth Statement I and Statement II are true
  2. BStatement I is true but Statement II is false
  3. CStatement I is false but Statement II is true
  4. DBoth Statement I and Statement II are false

Correct answer

A. Both Statement I and Statement II are true

Step-by-step solution

Statement I: f(x)=x1+∣x∣f(x) = \frac{x}{1+|x|}. For x≥0x \geq 0, f(x)=x1+xf(x) = \frac{x}{1+x} is strictly increasing. For x<0x < 0, f(x)=x1−xf(x) = \frac{x}{1-x} with f′(x)=1(1−x)2>0f'(x) = \frac{1}{(1-x)^2} > 0, also strictly increasing. The function is continuous at x=0x = 0, so ff is strictly increasing on R\mathbb{R} and hence one-one. Statement I is true.
Statement II: f(x)=x2+4x−30x2−8x+18f(x) = \frac{x^2+4x-30}{x^2-8x+18}. The denominator (x−4)2+2>0(x-4)^2 + 2 > 0 for all xx.
f′(x)=−12(x2−8x+14)(x2−8x+18)2f'(x) = \frac{-12(x^2 - 8x + 14)}{(x^2 - 8x + 18)^2}
f′(x)=0⇒x=4±2f'(x) = 0 \Rightarrow x = 4 \pm \sqrt{2}. Since f′f' changes sign, ff is not monotonic and hence many-one. Statement II is true.
Both statements are true.
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