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Consider the function whose formula is f(x) = rac16−x4x2−4. Find f(2) and _x -2 f(x).

Mathematics

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Answer

undefined

lim⁡x→−2f(x)=−8\lim_{x \to -2} f(x) = -8

Step-by-step solution

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SECTION B (20 Marks)

I. Consider the function whose formula is f(x)=16−x4x2−4f(x) = \frac{16-x^4}{x^2-4}. Find f(2)f(2) and lim⁡x→−2f(x)\lim_{x \to -2} f(x).

  1. Find f(2)f(2).

    Substitute x=2x=2 into the function:

    f(2)=16−(2)4(2)2−4=16−164−4=00f(2) = \frac{16-(2)^4}{(2)^2-4} = \frac{16-16}{4-4} = \frac{0}{0}

    Since this is an indeterminate form, the function is undefined at x=2x=2.

    f(2) is undefinedf(2) \text{ is undefined}
  2. Find lim⁡x→−2f(x)\lim_{x \to -2} f(x).

    First, attempt to substitute x=−2x=-2 into the function:

    f(−2)=16−(−2)4(−2)2−4=16−164−4=00f(-2) = \frac{16-(-2)^4}{(-2)^2-4} = \frac{16-16}{4-4} = \frac{0}{0}

    This is an indeterminate form, so we need to simplify the function by factoring.

  3. Factorize the numerator and denominator.

    The numerator is a difference of squares: 16−x4=(4−x2)(4+x2)16-x^4 = (4-x^2)(4+x^2).
    The denominator is also a difference of squares: x2−4x^2-4.
    So, we can write f(x)f(x) as:

    f(x)=(4−x2)(4+x2)x2−4f(x) = \frac{(4-x^2)(4+x^2)}{x^2-4}

    Notice that (4−x2)=−(x2−4)(4-x^2) = -(x^2-4). Substitute this into the expression:

    f(x)=−(x2−4)(4+x2)x2−4f(x) = \frac{-(x^2-4)(4+x^2)}{x^2-4}
  4. Simplify the function.

    For x2−4≠0x^2-4 \neq 0 (i.e., x≠2x \neq 2 and x≠−2x \neq -2), we can cancel the common factor (x2−4)(x^2-4):

    f(x)=−(4+x2)f(x) = -(4+x^2)
  5. Evaluate the limit.

    Now, find the limit as x→−2x \to -2 for the simplified function:

    lim⁡x→−2f(x)=lim⁡x→−2−(4+x2)\lim_{x \to -2} f(x) = \lim_{x \to -2} -(4+x^2)

    Substitute x=−2x=-2 into the simplified expression:

    =−(4+(−2)2)= -(4+(-2)^2) =−(4+4)= -(4+4) =−8= -8

    The final answers are:
    f(2)f(2) is undefined
    lim⁡x→−2f(x)=−8\lim_{x \to -2} f(x) = \boxed{-8}

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