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JEE Main 20266 AprilEvening Shift
Exam
JEE Main
Year
2026
Date
6 April
Shift
Evening Shift
Subject
Mathematics
Chapter
Functions

JEE Main 2026 · 6 April · Evening Shift · Mathematics · Functions

Let f: ℝ arrow ℝ be defined as f(x) = (2x^2 - 3x + 2)/(3x^2 + x +...

Let f:R→Rf: \mathbb{R} \rightarrow \mathbb{R} be defined as f(x)=2x2−3x+23x2+x+3f(x) = \dfrac{2x^2 - 3x + 2}{3x^2 + x + 3}. Then ff is :

Options

  1. Aboth one-one and onto
  2. Bone-one but not onto
  3. Conto but not one-one
  4. Dneither one-one nor onto

Correct answer

D. neither one-one nor onto

Step-by-step solution

Given f(x)=2x2−3x+23x2+x+3f(x) = \dfrac{2x^2 - 3x + 2}{3x^2 + x + 3}

To check for one-one, let f(x)=f(y)f(x) = f(y)

2x2−3x+23x2+x+3=2y2−3y+23y2+y+3\dfrac{2x^2 - 3x + 2}{3x^2 + x + 3} = \dfrac{2y^2 - 3y + 2}{3y^2 + y + 3}

Cross-multiplying and simplifying, we get:

11x2y−11xy2−11x+11y=011x^2y - 11xy^2 - 11x + 11y = 0

11xy(x−y)−11(x−y)=011xy(x - y) - 11(x - y) = 0

11(x−y)(xy−1)=011(x - y)(xy - 1) = 0

This implies x=yx = y or xy=1xy = 1.

Since f(x)=f(1/x)f(x) = f(1/x) for x≠0x \neq 0 (for example, f(2)=f(1/2)=417f(2) = f(1/2) = \dfrac{4}{17}), the function is many-one (not one-one).

To check for onto, let y=2x2−3x+23x2+x+3y = \dfrac{2x^2 - 3x + 2}{3x^2 + x + 3}

(3y−2)x2+(y+3)x+(3y−2)=0(3y - 2)x^2 + (y + 3)x + (3y - 2) = 0

For x∈Rx \in \mathbb{R}, the discriminant D≥0D \ge 0:

(y+3)2−4(3y−2)2≥0(y + 3)^2 - 4(3y - 2)^2 \ge 0

(y+3−6y+4)(y+3+6y−4)≥0(y + 3 - 6y + 4)(y + 3 + 6y - 4) \ge 0

(7−5y)(7y−1)≥0(7 - 5y)(7y - 1) \ge 0

(5y−7)(7y−1)≤0(5y - 7)(7y - 1) \le 0

y∈[17,75]y \in \left[\dfrac{1}{7}, \dfrac{7}{5}\right]

Since the range is a proper subset of the codomain R\mathbb{R}, the function is not onto.

Thus, ff is neither one-one nor onto.

Answer: neither one-one nor onto
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