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Given the function $p(x) = \left( \frac{1}{3} \right)^x$: 4.1.1 Is $p$ an increasing or decreasing function? 4.1.2 Determine $p^{-1}$, the inverse of $p$, in the form $y = ...$ 4.1.3 Write down the domain of $p^{-1}$ - NSC Mathematics - Question 4 - 2023 - Paper 1

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Given-the-function-$p(x)-=-\left(-\frac{1}{3}-\right)^x$:--4.1.1-Is-$p$-an-increasing-or-decreasing-function?--4.1.2-Determine-$p^{-1}$,-the-inverse-of-$p$,-in-the-form-$y-=-...$--4.1.3-Write-down-the-domain-of-$p^{-1}$-NSC Mathematics-Question 4-2023-Paper 1.png

Given the function $p(x) = \left( \frac{1}{3} \right)^x$: 4.1.1 Is $p$ an increasing or decreasing function? 4.1.2 Determine $p^{-1}$, the inverse of $p$, in the f... show full transcript

Worked Solution & Example Answer:Given the function $p(x) = \left( \frac{1}{3} \right)^x$: 4.1.1 Is $p$ an increasing or decreasing function? 4.1.2 Determine $p^{-1}$, the inverse of $p$, in the form $y = ...$ 4.1.3 Write down the domain of $p^{-1}$ - NSC Mathematics - Question 4 - 2023 - Paper 1

Step 1

Is $p$ an increasing or decreasing function?

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Answer

To determine if p(x)p(x) is an increasing or decreasing function, we analyze the base of the function, which is rac{1}{3}. Since rac{1}{3} < 1, the function p(x)p(x) is a decreasing function.

Step 2

Determine $p^{-1}$, the inverse of $p$, in the form $y = ...$

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Answer

To find the inverse of p(x)p(x):

  1. Start with y=(13)xy = \left( \frac{1}{3} \right)^x.
  2. Swap xx and yy: x=(13)yx = \left( \frac{1}{3} \right)^y.
  3. Take the logarithm of both sides: log13(x)=y\log_{\frac{1}{3}}(x) = y.

Thus, the inverse is p1(x)=log13(x)p^{-1}(x) = \log_{\frac{1}{3}}(x).

Step 3

Write down the domain of $p^{-1}$.

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Answer

The domain of the inverse function p1(x)=log13(x)p^{-1}(x) = \log_{\frac{1}{3}}(x) is x>0x > 0, since logarithms are defined only for positive numbers.

Step 4

Write down the equation of the asymptote of $p(x) - 5$.

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The asymptote of the function p(x)p(x) occurs where p(x)p(x) approaches a constant as xx approaches infinity. Thus, for p(x)5p(x) - 5, the equation of the asymptote is y=5y = -5.

Step 5

Write down the equations of the asymptotes of $f$.

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Answer

The function f(x)=4x1+2f(x) = \frac{4}{x - 1} + 2 has:

  • A vertical asymptote at x=1x = 1 (where the denominator is zero).
  • A horizontal asymptote at y=2y = 2 (as xx \to \infty).

Step 6

Calculate the x-intercept of $f$.

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Answer

To find the x-intercept, set f(x)=0f(x) = 0:

0=4x1+20 = \frac{4}{x - 1} + 2

Rearranging gives:

4x1=24=2(x1)4=2x+22=2xx=1\frac{4}{x - 1} = -2 \\ 4 = -2(x - 1) \\ 4 = -2x + 2 \\ 2 = -2x \\ x = -1

Thus, the x-intercept is x=1x = -1.

Step 7

Sketch the graph of $f$, label all asymptotes and indicate the intercepts with the axes.

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Answer

To sketch the graph of f(x)f(x):

  1. Mark the vertical asymptote at x=1x = 1 and the horizontal asymptote at y=2y = 2.
  2. Plot the x-intercept at (1,0)(-1, 0).
  3. The graph approaches the horizontal asymptote as xx approaches infinity and diverges as it approaches the vertical asymptote.

Step 8

Use your graph to determine the values of $x$ for which $\frac{4}{x - 1} = -2$.

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Answer

To find the values of xx for which 4x1=2\frac{4}{x - 1} = -2, we solve:

  1. From our previous calculation: x=2x = 2

Thus, x=2x = 2 is the value satisfying the equation.

Step 9

Determine the equation of the axis of symmetry of $f(x - 2)$, that has a negative gradient.

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Answer

The axis of symmetry for the function f(x2)=4(x2)1+2f(x - 2) = \frac{4}{(x - 2) - 1} + 2 is determined by finding the x-coordinate of the vertex. The transformation f(x2)f(x - 2) shifts the function two units to the right. The symmetry line would be at x=2x = 2, with a negative gradient of the original function.

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