Functions
Functional Equations
JEE Main 2023
Grade 12

Question:

Let $f : \mathbb{R} - \{0, 1\} \to \mathbb{R}$ satisfy $f(x) + f\left(\frac{1}{1-x}\right) = 1 + x$. Then $f(2)$ equals:
(1) $\frac{7}{4}$
(2) $2$
(3) $\frac{9}{4}$
(4) $\frac{5}{2}$

Step-by-Step Solution

Key Concept: Write the equation at $x = 2$, at $x = -1$ (i.e. $1/(1 - 2)$), and at $x = 1/2$. This gives three equations in $f(2), f(-1), f(1/2)$ — solve the linear system.
The detailed step-by-step mathematical proof is available inside the Mathbee app workspace.
Correct Answer: (3)

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