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Given: f(x) = 2^x + 1 4.1 Determine the coordinates of the y-intercept of f - NSC Mathematics - Question 4 - 2016 - Paper 1

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Given: f(x) = 2^x + 1 4.1 Determine the coordinates of the y-intercept of f. 4.2 Sketch the graph of f, clearly indicating ALL intercepts with the axes as we... show full transcript

Worked Solution & Example Answer:Given: f(x) = 2^x + 1 4.1 Determine the coordinates of the y-intercept of f - NSC Mathematics - Question 4 - 2016 - Paper 1

Step 1

Determine the coordinates of the y-intercept of f.

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Answer

To determine the y-intercept of the function f(x) = 2^x + 1, we substitute x = 0 into the function:

f(0)=20+1=1+1=2f(0) = 2^0 + 1 = 1 + 1 = 2

Therefore, the coordinates of the y-intercept are (0; 2).

Step 2

Sketch the graph of f, clearly indicating ALL intercepts with the axes as well as any asymptotes.

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Answer

The graph of the function f(x) = 2^x + 1 has the following characteristics:

  • Y-Intercept: (0; 2)
  • X-Intercept: Since f(x) = 0 has no solution for the equation 2^x + 1 = 0, there is no x-intercept.
  • Asymptote: The horizontal asymptote occurs at y = 1, as the function approaches y = 1 as x approaches negative infinity.

The graph is an exponential function that increases without bound as x increases, and it approaches y = 1 but never touches it.

Step 3

Calculate the average gradient of f between the points on the graph where x = -2 and x = 1.

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Answer

To find the average gradient between x = -2 and x = 1, we need to calculate the values of f at these points:

f(2)=22+1=14+1=54f(-2) = 2^{-2} + 1 = \frac{1}{4} + 1 = \frac{5}{4}

f(1)=21+1=2+1=3f(1) = 2^1 + 1 = 2 + 1 = 3

Now, we can use the formula for the average gradient:

Average Gradient=f(1)f(2)1(2)=3543=124543=743=712\text{Average Gradient} = \frac{f(1) - f(-2)}{1 - (-2)} = \frac{3 - \frac{5}{4}}{3} = \frac{\frac{12}{4} - \frac{5}{4}}{3} = \frac{\frac{7}{4}}{3} = \frac{7}{12}

Step 4

If h(x) = 3f(x), write down an equation of the asymptote of h.

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Answer

Since the asymptote of f is y = 1, the asymptote of h(x) = 3f(x) will be:

y = 3(1) = 3.

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