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Let f(x)={((a|x^(2)-x-2|)/(2+x-x^(2)), ,...

Let `f(x)={((a|x^(2)-x-2|)/(2+x-x^(2)), , xlt2),(b, , x=2),((x-[x])/(x-2), , xgt2):}`
([.]denotes thet greatest integer functional). If `f(x)` is continuous at x=2 then:

A

`a=1, b=2`

B

`a=1, b=1`

C

`a=0, b=1`

D

`a=2, b=1`

Text Solution

AI Generated Solution

The correct Answer is:
To determine the values of \( a \) and \( b \) such that the function \( f(x) \) is continuous at \( x = 2 \), we will analyze the function piece by piece. ### Step 1: Define the function at \( x = 2 \) The function \( f(x) \) is defined as follows: - For \( x < 2 \): \[ f(x) = \frac{a |x^2 - x - 2|}{2 + x - x^2} \] - For \( x = 2 \): \[ f(x) = b \] - For \( x > 2 \): \[ f(x) = \frac{x - [x]}{x - 2} \] ### Step 2: Find the limit as \( x \) approaches 2 from the left First, we need to evaluate the limit of \( f(x) \) as \( x \) approaches 2 from the left (\( x \to 2^- \)): \[ f(2^-) = \lim_{x \to 2^-} \frac{a |x^2 - x - 2|}{2 + x - x^2} \] We simplify \( |x^2 - x - 2| \): \[ x^2 - x - 2 = (x - 2)(x + 1) \] For \( x < 2 \), \( |x^2 - x - 2| = -(x^2 - x - 2) = -((x - 2)(x + 1)) \). Now, substituting this into the limit: \[ f(2^-) = \lim_{x \to 2^-} \frac{a(-(x - 2)(x + 1))}{2 + x - x^2} \] Next, simplify the denominator: \[ 2 + x - x^2 = 2 + 2 - 4 = 0 \quad \text{(as \( x \to 2 \))} \] Thus, we need to factor the denominator: \[ 2 + x - x^2 = -(x^2 - x - 2) = -(x - 2)(x + 1) \] Now we have: \[ f(2^-) = \lim_{x \to 2^-} \frac{a(-(x - 2)(x + 1))}{-(x - 2)(x + 1)} = a \] ### Step 3: Find the limit as \( x \) approaches 2 from the right Next, we evaluate the limit of \( f(x) \) as \( x \) approaches 2 from the right (\( x \to 2^+ \)): \[ f(2^+) = \lim_{x \to 2^+} \frac{x - [x]}{x - 2} \] For \( 2 < x < 3 \), \( [x] = 2 \), so: \[ f(2^+) = \lim_{x \to 2^+} \frac{x - 2}{x - 2} = 1 \] ### Step 4: Set the limits equal for continuity For \( f(x) \) to be continuous at \( x = 2 \), we need: \[ f(2^-) = f(2) = f(2^+) \] This gives us: \[ a = b = 1 \] ### Conclusion Thus, the values of \( a \) and \( b \) are: \[ \boxed{1} \]
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