Photo AI

The function f is defined by f: x ↦ ln(4 − 2x), x < 2 and x ∈ ℝ - Edexcel - A-Level Maths Pure - Question 7 - 2007 - Paper 6

Question icon

Question 7

The-function-f-is-defined-by--f:-x-↦-ln(4-−-2x),--x-<-2-and--x-∈-ℝ-Edexcel-A-Level Maths Pure-Question 7-2007-Paper 6.png

The function f is defined by f: x ↦ ln(4 − 2x), x < 2 and x ∈ ℝ. (a) Show that the inverse function of f is defined by f^(-1): x ↦ 2 - rac{1}{2}e^x and write ... show full transcript

Worked Solution & Example Answer:The function f is defined by f: x ↦ ln(4 − 2x), x < 2 and x ∈ ℝ - Edexcel - A-Level Maths Pure - Question 7 - 2007 - Paper 6

Step 1

Show that the inverse function of f is defined by f^(-1): x ↦ 2 - rac{1}{2}e^x

96%

114 rated

Answer

To find the inverse function, we start with the equation of f:

y=extln(42x)y = ext{ln}(4 - 2x)

To express x in terms of y, we rearrange this:

  1. Exponentiate both sides: ey=42xe^y = 4 - 2x
  2. Rearranging gives: 2x=4ey2x = 4 - e^y
  3. Dividing by 2 yields: x = 2 - rac{1}{2}e^y

Thus, we conclude:

f^{-1}(x) = 2 - rac{1}{2}e^x

Next, the domain of f^(-1) corresponds to the range of f, which is limited to the values that f can attain. Given that f is defined for x < 2, we find that the domain of f^(-1) is:

f1:xextisin(ext,extln(4))f^{-1}: x ext{ is in } (- ext{∞}, ext{ln}(4))

Step 2

Write down the range of f^(-1).

99%

104 rated

Answer

The range of f^(-1) can be determined from our earlier findings. As x approaches -∞, f^(-1)(x) approaches 2. Thus, we conclude that:

extRangeoff1=(2,ext) ext{Range of } f^{-1} = (2, ext{∞})

Step 3

In the space provided on page 16, sketch the graph of y = f^(-1)(x). State the coordinates of the points of intersection with the x and y axes.

96%

101 rated

Answer

The graph of y = f^(-1)(x) is a transformed exponential curve. The intersection with the y-axis occurs when x = 0:

f^{-1}(0) = 2 - rac{1}{2}e^0 = 2 - rac{1}{2} = 1.5

So, the point is (0, 1.5).

The intersection with the x-axis occurs when y = 0:

0 = 2 - rac{1}{2}e^x

Solving gives:

ightarrow x = ext{ln}(4)$$ Thus, the point is (ln(4), 0).

Step 4

Calculate the values of x_1 and x_2, giving your answers to 4 decimal places.

98%

120 rated

Answer

Using the iterative formula:

  1. Start with x_0 = -0.3:

ewline ≈ -0.3515$$

  1. For x_1 = -0.3515:

ewline ≈ -0.3522$$

Both values should be provided to 4 decimal places:

Thus, x_1 ≈ -0.3515 and x_2 ≈ -0.3522.

Step 5

Find the value of k to 3 decimal places.

97%

117 rated

Answer

To find k, we determine the limit of x_n as n approaches infinity. Notice that this requires additional iterations beyond x_2:

Assuming we continue the iteration until convergence, we see that:

kextconvergesto0.352k ext{ converges to } -0.352

Thus, the value is: k=0.352k = -0.352

Join the A-Level students using SimpleStudy...

97% of Students

Report Improved Results

98% of Students

Recommend to friends

100,000+

Students Supported

1 Million+

Questions answered

;