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The point P(1, a) lies on the curve with equation $y = (x + 1)^{2}(2 - x)$ - Edexcel - A-Level Maths Pure - Question 10 - 2009 - Paper 1

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The point P(1, a) lies on the curve with equation $y = (x + 1)^{2}(2 - x)$. (a) Find the value of a. (b) On the axes below sketch the curves with the following e... show full transcript

Worked Solution & Example Answer:The point P(1, a) lies on the curve with equation $y = (x + 1)^{2}(2 - x)$ - Edexcel - A-Level Maths Pure - Question 10 - 2009 - Paper 1

Step 1

Find the value of a.

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Answer

To find the value of a, we substitute x = 1 into the equation of the curve, yielding:

y=(1+1)2(21)=22(1)=4.y = (1 + 1)^{2}(2 - 1) = 2^{2}(1) = 4.
Thus, the coordinates of point P are (1, 4), so:

a=4.a = 4.

Step 2

On the axes below sketch the curves with the following equations: (i) y = (x + 1)^{2}(2 - x)

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The curve y=(x+1)2(2x)y = (x + 1)^{2}(2 - x) is a cubic function. It has a minimum at x = -1 and its maximum intersection point can be calculated and sketched as follows:

  1. Identify intercepts:
    • For the y-intercept (when x = 0):
      y=(0+1)2(20)=12(2)=2.y = (0 + 1)^{2}(2 - 0) = 1^{2}(2) = 2.
    • For x-intercept (setting y=0):
      0=(x+1)2(2x)=>(x+1)2=0extor(2x)=00 = (x + 1)^{2}(2 - x) => (x + 1)^{2} = 0 ext{ or } (2 - x) = 0 yielding x = -1 or x = 2.
  2. Plot these critical points on the graph (0, 2), (-1, 0), and (2, 0).
  3. Sketch the curve through these points, ensuring it displays a minimum at (-1, 0) and intersects the axes at the calculated points.

Step 3

On the axes below sketch the curves with the following equations: (ii) y = \frac{2}{x}

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The curve y=2xy = \frac{2}{x} is a hyperbola. It has the following characteristics:

  1. Asymptotes at both axes.
  2. Intersects the y-axis at (0, 2).
  3. Intersects the x-axis at (2, 0), although x cannot actually be zero.
  4. Sketch this hyperbola in each quadrant avoiding the axes.
  5. Clearly denote the shape for both curves, indicating where they meet the axes and their attributes on the graph.

Step 4

With reference to your diagram in part (b) state the number of real solutions to the equation (x + 1)^{2}(2 - x) = \frac{2}{x}.

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Answer

To find the number of real solutions, observe the intersections of the curves from part (b).

  1. The first curve has at least two intersection points in the positive quadrant (roots) given its behavior.
  2. Since the second curve approaches infinity but never touches the x-axis, the two curves, therefore, intersect at two points.
    This results in exactly two solutions to the equation.

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