Figure 1 shows a sketch of the curve with equation $y = \frac{2}{x}$, $x \neq 0$ - Edexcel - A-Level Maths Pure - Question 7 - 2013 - Paper 3
Question 7
Figure 1 shows a sketch of the curve with equation $y = \frac{2}{x}$, $x \neq 0$.
The curve C has equation $y = \frac{2}{x} - 5$, $x \neq 0$, and the line l has equ... show full transcript
Worked Solution & Example Answer:Figure 1 shows a sketch of the curve with equation $y = \frac{2}{x}$, $x \neq 0$ - Edexcel - A-Level Maths Pure - Question 7 - 2013 - Paper 3
Step 1
Sketch and clearly label the graphs of C and l on a single diagram.
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Answer
To illustrate the graphs of both curves, we start by plotting the graph of the curve C, which is defined by the function y=x2−5. This function has a vertical asymptote at x=0 and a horizontal asymptote at y=−5. The graph of the line l defined by y=4x+2 will be a straight line that crosses the y-axis at (0,2) and has a slope of 4.
Coordinates of Intersections:
For curve C:
x-intercept: Set y=0:
0=x2−5⟹x2=5⟹x=52
Thus, the x-intercept is at (52,0).
For line l:
x-intercept: Set y=0:
0=4x+2⟹4x=−2⟹x=−21
Thus, the x-intercept is at (−21,0).
The y-intercept of C can be found by substituting x:
y=12−5=−3
Thus, the y-intercept is at (0,−3).
Step 2
Write down the equations of the asymptotes of the curve C.
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Answer
The equations of the asymptotes for curve C are:
Vertical Asymptote: x=0
Horizontal Asymptote: y=−5
Step 3
Find the coordinates of the points of intersection of $y = \frac{2}{x} - 5$ and $y = 4x + 2$.
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Answer
To find the points of intersection, we set the functions equal to each other:
x2−5=4x+2
Rearranging gives:
x2=4x+7
Multiplying both sides by x (where x=0) results in:
2=4x2+7x
Rearranging results in:
4x2+7x−2=0
Applying the quadratic formula, we have:
x=2a−b±b2−4ac=2⋅4−7±72−4⋅4⋅(−2)
This simplifies to:
x=8−7±49+32=8−7±81=8−7±9
Thus, we find two potential x values:
x1=82=41
x2=8−16=−2
Now substituting back to find corresponding y values: