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Figure 1 shows part of the curve with equation $x=4e^{t/3} + 3$ - Edexcel - A-Level Maths Pure - Question 7 - 2013 - Paper 1

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Figure 1 shows part of the curve with equation $x=4e^{t/3} + 3$. The finite region $R$ shown shaded in Figure 1 is bounded by the curve, the x-axis, the t-axis and t... show full transcript

Worked Solution & Example Answer:Figure 1 shows part of the curve with equation $x=4e^{t/3} + 3$ - Edexcel - A-Level Maths Pure - Question 7 - 2013 - Paper 1

Step 1

Complete the table with the value of $x$ corresponding to $t = 6$, giving your answer to 3 decimal places.

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Answer

To find the value of xx for t=6t = 6, we substitute tt into the equation:

x=4e6/3+3=4e2+3x = 4e^{6/3} + 3 = 4e^2 + 3

Calculating this gives:

xextapproximatelyequals4(7.389)+3extwhichis29.556.x ext{ approximately equals } 4(7.389) + 3 ext{ which is } 29.556.

Thus, xx corresponding to t=6t = 6 is approximately 29.556.

Step 2

Use the trapezium rule with all the values of $x$ in the completed table to obtain an estimate for the area of the region $R$, giving your answer to 2 decimal places.

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Answer

Using the trapezium rule, the area can be estimated using the formula:

ext{Area} = rac{h}{2} (y_0 + 2y_1 + 2y_2 + ... + 2y_{n-1} + y_n)

where hh is the width of each interval. Here:

  • h=2h = 2 (since (80)/4=2(8 - 0) / 4 = 2)
  • y0=3y_0 = 3, y1=7.107y_1 = 7.107, y2=7.218y_2 = 7.218, y3=29.556y_3 = 29.556, y4=5.223y_4 = 5.223.

Calculating the area:

ext{Area} = rac{2}{2} (3 + 2(7.107) + 2(7.218) + 2(29.556) + 5.223) = 49.37

Thus, the estimated area is approximately 49.37.

Step 3

Use calculus to find the exact value for the area of $R$.

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Answer

To find the exact area under the curve, we evaluate the integral:

A = ext{Area} = int_0^8 (4e^{t/3} + 3) \, dt

Calculating gives:

A=[12et/3+3t]08=12e8/3+24(12+0)=12(e8/31)+24A = [12e^{t/3} + 3t]_{0}^{8} = 12e^{8/3} + 24 - (12 + 0) = 12(e^{8/3} - 1) + 24

Evaluating this precisely yields approximately 49.369.

Step 4

Find the difference between the values obtained in part (b) and part (c), giving your answer to 2 decimal places.

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Answer

The estimated area from part (b) is 49.37 and the exact area from part (c) is approximately 49.369.

The difference is:

49.3749.369=0.00149.37 - 49.369 = 0.001

Thus, the difference is approximately 0.00 when rounded to 2 decimal places.

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