The diagram shows part of the curve with equation $y = x^3 - 2x^2 - 4x + 1$ and the line with equation $y = x - 5$ - Scottish Highers Maths - Question 8 - 2023
Question 8
The diagram shows part of the curve with equation $y = x^3 - 2x^2 - 4x + 1$ and the line with equation $y = x - 5$.
The curve and the line intersect at the points w... show full transcript
Worked Solution & Example Answer:The diagram shows part of the curve with equation $y = x^3 - 2x^2 - 4x + 1$ and the line with equation $y = x - 5$ - Scottish Highers Maths - Question 8 - 2023
Step 1
Integrate using "upper - lower"
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Answer
To find the shaded area between the curve and the line, we need to evaluate the integral of the difference between the two functions from their intersection points, which are given as x=−2 and x=1.
We will calculate:
extArea=∫−21((x−5)−(x3−2x2−4x+1))dx
Step 2
Identify limits
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Answer
The limits of integration are set from x=−2 to x=1.
Step 3
Integrate both functions
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Answer
Now we simplify the integrand:
(x−5)−(x3−2x2−4x+1)=−x3+2x2+5−4x
Thus, the integral becomes:
∫−21(−x3+2x2−4x+4)dx
Step 4
Substitute limits
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Answer
Next, we calculate the definite integral:
∫(−x3+2x2−4x+4)dx=−41x4+32x3−2x2+4x
Substituting the limits:
=[−41(1)4+32(1)3−2(1)2+4(1)]−[−41(−2)4+32(−2)3−2(−2)2+4(−2)]
Step 5
Calculate shaded area
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Answer
Calculating these expressions:
For x=1:
−41(1)+32(1)−2(1)+4(1)=−41+32−2+4=129+126−1224=12−9
For x=−2:
−41(16)+32(−8)−2(4)−8=−4−316−8=−4+8−316=−312−316=3−28
Finally, the total area is:
(−129−(−328))=(−129+12112)=12103
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