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Gegee: f(x) = x(x - 3)^2 met f' (1) = f' (3) = 0 en f(1) = 4 8.1 Toon dat f 'n buigpunt by x = 2 het - NSC Mathematics - Question 8 - 2017 - Paper 1

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Gegee:---f(x)-=-x(x---3)^2-met-f'-(1)-=-f'-(3)-=-0-en-f(1)-=-4--8.1-Toon-dat-f-'n-buigpunt-by-x-=-2-het-NSC Mathematics-Question 8-2017-Paper 1.png

Gegee: f(x) = x(x - 3)^2 met f' (1) = f' (3) = 0 en f(1) = 4 8.1 Toon dat f 'n buigpunt by x = 2 het. 8.2 Skets die grafiek van f en dui die afsnitte met die ass... show full transcript

Worked Solution & Example Answer:Gegee: f(x) = x(x - 3)^2 met f' (1) = f' (3) = 0 en f(1) = 4 8.1 Toon dat f 'n buigpunt by x = 2 het - NSC Mathematics - Question 8 - 2017 - Paper 1

Step 1

8.1 Toon dat f 'n buigpunt by x = 2 het.

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Answer

To find the inflection point, we need to determine where the second derivative changes sign. First, we compute the first derivative:

f(x)=3x26x+9f'(x) = 3x^2 - 6x + 9

Next, we find the second derivative:

f(x)=6x6f''(x) = 6x - 6

Setting the second derivative equal to zero gives:

6x = 6 \\ x = 1$$ We check the sign of the second derivative around this point. For x < 1, say x = 0, we have: $$f''(0) = 6(0) - 6 = -6 < 0$$ And for x > 1, say x = 2: $$f''(2) = 6(2) - 6 = 6 > 0$$ Thus, the concavity changes at x = 1, indicating a point of inflection at x = 2.

Step 2

8.2 Skets die grafiek van f en dui die afsnitte met die asse en die draai punte duidelik aan.

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Answer

To sketch the graph of f, we need to identify key points including the x-intercepts and y-intercept. We previously found that:

  • The x-intercepts occur at x = 0 and x = 3 (from setting f(x) = 0).
  • The y-intercept is found by evaluating f(0):

f(0)=0(03)2=0f(0) = 0(0 - 3)^2 = 0

  • The maximum occurs at (1, 4).

Plotting these points will give a rough sketch of the graph, clearly marking the points of intersection with the axes and indicating the points of inflection at x = 1.

Step 3

8.3 Vir watter waardes van x sal y = -f(x) konkav na onder wees?

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Answer

The function y=f(x)y = -f(x) will be concave down where the second derivative of f(x)f(x) is positive, as the negative of a function flips the concavity. We previously found f(x)=6x6f''(x) = 6x - 6. Setting this greater than zero:

6x > 6 \\ x > 1$$ Therefore, for $x > 1$, $y = -f(x)$ will be concave down.

Step 4

8.4.1 Bepaal die koördinate van die lokale maksimum van h indien h(x) = f(x - 2) + 3.

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Answer

To find the local maximum of h(x)h(x), we first evaluate the transformation. Since h(x)=f(x2)+3h(x) = f(x - 2) + 3, we shift the graph of f(x)f(x) to the right by 2 units and then up by 3 units. The local maximum from f(x)f(x), which occurs at (1, 4) in the original function, becomes:

h(3)=f(1)+3=4+3=7h(3) = f(1) + 3 = 4 + 3 = 7

Thus, the local maximum coordinate in h(x) is (3, 7).

Step 5

8.4.2 Claire beweer dat f ' (2) = 1.

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Answer

To verify Claire's assertion, we compute the first derivative at x = 2:

f(x)=3x26x+9f'(x) = 3x^2 - 6x + 9

Substituting x = 2 gives:

e 1$$ Thus, we do not agree with Claire; her statement is incorrect. The gradient at x = 2 is 9, not 1.

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