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Let A=R-{3}, B=R-{1}. Let f:ArarrB be de...

Let `A=R-{3}, B=R-{1}.` Let `f:ArarrB` be defined by `f(x)=((x-2)/(x-3))`, then

A

a. f is bijective

B

b. Surjective

C

c. Injective

D

d. None of above

Text Solution

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The correct Answer is:
To solve the problem, we need to analyze the function \( f: A \to B \) defined by \( f(x) = \frac{x - 2}{x - 3} \), where \( A = \mathbb{R} \setminus \{3\} \) and \( B = \mathbb{R} \setminus \{1\} \). ### Step 1: Determine if the function is injective (one-to-one) To check if the function is injective, we need to show that if \( f(x_1) = f(x_2) \), then \( x_1 = x_2 \). 1. Start with the equation: \[ f(x_1) = f(x_2) \] This implies: \[ \frac{x_1 - 2}{x_1 - 3} = \frac{x_2 - 2}{x_2 - 3} \] 2. Cross-multiply to eliminate the fractions: \[ (x_1 - 2)(x_2 - 3) = (x_2 - 2)(x_1 - 3) \] 3. Expand both sides: \[ x_1x_2 - 3x_1 - 2x_2 + 6 = x_2x_1 - 3x_2 - 2x_1 + 6 \] 4. Simplify: \[ -3x_1 - 2x_2 = -3x_2 - 2x_1 \] Rearranging gives: \[ -3x_1 + 2x_1 = -3x_2 + 2x_2 \] Which simplifies to: \[ -x_1 = -x_2 \quad \text{or} \quad x_1 = x_2 \] Since we have shown that \( f(x_1) = f(x_2) \) implies \( x_1 = x_2 \), the function \( f \) is injective. ### Step 2: Determine if the function is surjective (onto) To check if the function is surjective, we need to show that for every \( y \in B \), there exists an \( x \in A \) such that \( f(x) = y \). 1. Set \( f(x) = y \): \[ y = \frac{x - 2}{x - 3} \] 2. Rearranging gives: \[ y(x - 3) = x - 2 \] This leads to: \[ yx - 3y = x - 2 \] 3. Rearranging terms: \[ yx - x = 3y - 2 \] Factor out \( x \): \[ x(y - 1) = 3y - 2 \] 4. Solving for \( x \): \[ x = \frac{3y - 2}{y - 1} \] 5. We need to ensure that \( x \) is defined and belongs to \( A \). The function \( x \) is undefined when \( y = 1 \), which is excluded from set \( B \). Since for every \( y \in B \) (where \( y \neq 1 \)), we can find an \( x \in A \) such that \( f(x) = y \), the function \( f \) is surjective. ### Conclusion Since \( f \) is both injective and surjective, we conclude that \( f \) is bijective. ### Final Answer The function \( f \) is injective, surjective, and therefore bijective. ---
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