Verified Solution • 2025–26 Session moderate

QJEEM23Ma6b00: JEE Main 2023 Mathematics - Class 11 JEEM23Ma6b00 Solution: Let be real valued function defined as . Then range of is

Let f:R−{2,6}→Rf: \mathbb{R}-\{2,6\} \rightarrow \mathbb{R} be real valued function

defined as f(x)=x2+2x+1x2−8x+12f(x)=\frac{x^2+2 x+1}{x^2-8 x+12} .

Then range of ff is

Multiple Choice Options

  • A (−∞,−214]∪[1,∞)\left(-\infty,-\frac{21}{4}\right] \cup[1, \infty)
  • B (−∞,−214)∪(0,∞)\left(-\infty,-\frac{21}{4}\right) \cup(0, \infty)
  • C (−∞,−214]∪[0,∞)\left(-\infty,-\frac{21}{4}\right] \cup[0, \infty)
  • D (−∞,−214]∪[214,∞)\left(-\infty,-\frac{21}{4}\right] \cup\left[\frac{21}{4}, \infty\right)

Step-by-Step Verified Solution

y=x2+2x+1x2−8x+12y=\frac{x^{2}+2 x+1}{x^{2}-8 x+12}

⇒(y−1)x2−(8y+2)x+12y−1=0\Rightarrow(y-1) x^{2}-(8 y+2) x+12 y-1=0

Let y≠1y \neq 1 , then D≥0D \geq 0

4(4y+1)2−4(y−1)(12y−1)≥04(4 y+1)^{2}-4(y-1)(12 y-1) \geq 0

⇒16y2+1+8y−(12y2−13y+1)≥0\Rightarrow 16 y^{2}+1+8 y-\left(12 y^{2}-13 y+1\right) \geq 0

⇒4y2+21y≥0\Rightarrow 4 y^{2}+21 y \geq 0

⇒y∈(−∞,−214)∪[0,∞)−{1}\Rightarrow y \in\left(-\infty,-\frac{21}{4}\right) \cup[0, \infty)-\{1\}

 for y=1, \text { for } y=1 \text {, }

amp;−8x+12=2x+1amp;x=1110∴I∈R\begin{aligned}& -8 x+12=2 x+1 \\\\& x=\frac{11}{10} \quad \therefore I \in R\end{aligned}

∴\therefore Range =(−∞,−214]∪[0,∞)=\left(-\infty,-\frac{21}{4}\right] \cup[0, \infty)

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