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Let f (x) =(2 |x| -1)/(x-3) Range of f...

Let `f (x) =(2 |x| -1)/(x-3)`
Range of `f (x):`

A

`R- {3}`

B

`(-oo, (1)/(3) ] uu (2,oo)`

C

`(-2, (1)/(3)] uu (2,oo)`

D

R

Text Solution

AI Generated Solution

The correct Answer is:
To find the range of the function \( f(x) = \frac{2 |x| - 1}{x - 3} \), we will analyze the function for two cases based on the definition of the absolute value. ### Step 1: Analyze the function for \( x \geq 0 \) When \( x \geq 0 \), \( |x| = x \). Thus, the function simplifies to: \[ f(x) = \frac{2x - 1}{x - 3} \] Let \( f(x) = y \): \[ y = \frac{2x - 1}{x - 3} \] Cross-multiplying gives: \[ y(x - 3) = 2x - 1 \] Rearranging this, we have: \[ yx - 2x = 3y - 1 \] Factoring out \( x \): \[ x(y - 2) = 3y - 1 \] Thus, we can express \( x \) as: \[ x = \frac{3y - 1}{y - 2} \] Since \( x \geq 0 \), we need: \[ \frac{3y - 1}{y - 2} \geq 0 \] This inequality holds when both the numerator and denominator are positive or both are negative. ### Step 2: Determine when \( 3y - 1 \geq 0 \) 1. \( 3y - 1 \geq 0 \) implies: \[ y \geq \frac{1}{3} \] ### Step 3: Determine when \( y - 2 > 0 \) 2. \( y - 2 > 0 \) implies: \[ y > 2 \] ### Step 4: Combine the conditions From the analysis above, we have: - \( y \geq \frac{1}{3} \) - \( y > 2 \) Thus, for \( x \geq 0 \), the range of \( f(x) \) is \( [\frac{1}{3}, 2) \). ### Step 5: Analyze the function for \( x < 0 \) When \( x < 0 \), \( |x| = -x \). The function becomes: \[ f(x) = \frac{-2x - 1}{x - 3} \] Let \( f(x) = y \): \[ y = \frac{-2x - 1}{x - 3} \] Cross-multiplying gives: \[ y(x - 3) = -2x - 1 \] Rearranging this, we have: \[ yx + 2x = 3y - 1 \] Factoring out \( x \): \[ x(y + 2) = 3y - 1 \] Thus, we can express \( x \) as: \[ x = \frac{3y - 1}{y + 2} \] Since \( x < 0 \), we need: \[ \frac{3y - 1}{y + 2} < 0 \] This inequality holds when the numerator and denominator have opposite signs. ### Step 6: Determine when \( 3y - 1 < 0 \) 1. \( 3y - 1 < 0 \) implies: \[ y < \frac{1}{3} \] ### Step 7: Determine when \( y + 2 > 0 \) 2. \( y + 2 > 0 \) implies: \[ y > -2 \] ### Step 8: Combine the conditions From the analysis above, we have: - \( y < \frac{1}{3} \) - \( y > -2 \) Thus, for \( x < 0 \), the range of \( f(x) \) is \( (-2, \frac{1}{3}) \). ### Step 9: Combine both ranges Combining the ranges from both cases, we get: \[ \text{Range of } f(x) = (-2, \frac{1}{3}) \cup (2, \infty) \] ### Final Answer Thus, the range of \( f(x) \) is: \[ (-2, \frac{1}{3}) \cup (2, \infty) \]
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