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Complete the table below, giving the values of y to 2 decimal places - Edexcel - A-Level Maths Pure - Question 8 - 2011 - Paper 3

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Complete the table below, giving the values of y to 2 decimal places. | x | 2 | 2.25 | 2.5 | 2.75 | 3 | |-------|---|------|-----|------|---| | y | 0.5 | 0.... show full transcript

Worked Solution & Example Answer:Complete the table below, giving the values of y to 2 decimal places - Edexcel - A-Level Maths Pure - Question 8 - 2011 - Paper 3

Step 1

Complete the table below, giving the values of y to 2 decimal places.

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Answer

To complete the table, we need to calculate the values of yy using the formula y=53x22y = \frac{5}{3x^{2}-2} for each corresponding xx value:

  • For x=2x = 2: y=53(22)2=510=0.5y = \frac{5}{3(2^{2})-2} = \frac{5}{10} = 0.5
  • For x=2.25x = 2.25: y=53(2.252)2=515.187520.38y = \frac{5}{3(2.25^{2})-2} = \frac{5}{15.1875 - 2} \approx 0.38
  • For x=2.5x = 2.5: y=53(2.52)2=518.7520.32y = \frac{5}{3(2.5^{2})-2} = \frac{5}{18.75 - 2} \approx 0.32
  • For x=2.75x = 2.75: y=53(2.752)2=522.687520.24y = \frac{5}{3(2.75^{2})-2} = \frac{5}{22.6875 - 2} \approx 0.24
  • For x=3x = 3: y=53(32)2=5272=0.2y = \frac{5}{3(3^{2})-2} = \frac{5}{27 - 2} = 0.2

The completed table is:

x22.252.52.753
y0.50.380.320.240.2

Step 2

Use the trapezium rule, with all the values of y from your table, to find an approximate value for $\int_{2}^{3} \frac{5}{3x^{2}-2} \,dx$.

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Answer

The trapezium rule formula is given by: Aba2(f(a)+f(b))A \approx \frac{b-a}{2}(f(a) + f(b)) where f(a)f(a) and f(b)f(b) are the function values at aa and bb, respectively. For this question, we will also account for the other values:

The interval [2,3][2, 3] consists of values at x=2,2.25,2.5,2.75,3x = 2, 2.25, 2.5, 2.75, 3. We compute the area:

  • h=0.25h = 0.25 (the width of each sub-interval)
  • yy values are: f(2)=0.5f(2)=0.5, f(2.25)=0.38f(2.25)=0.38, f(2.5)=0.32f(2.5)=0.32, f(2.75)=0.24f(2.75)=0.24, and f(3)=0.2f(3)=0.2

Calculating the total area: A0.252(0.5+0.38+0.32+0.24+0.2)=0.125(0.5+0.38+0.32+0.24+0.2)=0.125×1.64=0.205A \approx \frac{0.25}{2}(0.5 + 0.38 + 0.32 + 0.24 + 0.2) = 0.125 (0.5 + 0.38 + 0.32 + 0.24 + 0.2) = 0.125 \times 1.64 = 0.205

Thus, the approximate value for the integral is 0.2050.205.

Step 3

Use your answer to part (b) to find an approximate value for the area of S.

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Answer

To find the area of region S, we have the trapezium rule calculated area as approximately 0.2050.205 from part (b). Since the area S is entirely below the curve and above the x-axis and the line through B at (2, 0), we can directly state that the approximate value for the area of S is 0.2050.205.

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