Find the coordinates of the stationary point of the curve with equation
$(x+y-2)^2 = e^y - 1$ - AQA - A-Level Maths Pure - Question 6 - 2018 - Paper 2
Question 6
Find the coordinates of the stationary point of the curve with equation
$(x+y-2)^2 = e^y - 1$
Worked Solution & Example Answer:Find the coordinates of the stationary point of the curve with equation
$(x+y-2)^2 = e^y - 1$ - AQA - A-Level Maths Pure - Question 6 - 2018 - Paper 2
Step 1
Select appropriate technique to differentiate
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Answer
To find the stationary points, we first need to differentiate the given equation implicitly, treating y as a function of x. We start by differentiating both sides of the equation:
2(x+y−2)(dxd(x+y−2))=eydxdy
Applying the chain rule to the left side gives us:
2(x+y−2)(1+dxdy)=eydxdy
Step 2
Differentiate term involving $e^y$ correctly
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Answer
Rearranging the differentiation leads to:
2(x+y−2)+2(x+y−2)dxdy=eydxdy
Step 3
Set $rac{dy}{dx} = 0$
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Answer
For stationary points, we set the derivative rac{dy}{dx} = 0:
2(x+y−2)=0
Step 4
Solve for $y$
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Answer
This simplifies to:
x+y−2=0⇒y=2−x
Step 5
Eliminate $x$ or $y$ from the equation of the curve
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Answer
Now, substituting y=2−x back into the original curve's equation:
(x+(2−x)−2)2=e(2−x)−1
This simplifies to:
0=e(2−x)−1⇒e(2−x)=1
Step 6
Obtain correct $y$
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Answer
Taking the natural logarithm, we find:
2−x=0⇒x=2
Substituting x=2 back into y=2−x, gives:
y=2−2=0
Step 7
Obtain correct $x$
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Answer
Thus, the coordinates of the stationary point are: