Figure 2 shows the straight line l₁ with equation 4y = 5x + 12 - Edexcel - A-Level Maths Pure - Question 9 - 2018 - Paper 1
Question 9
Figure 2 shows the straight line l₁ with equation 4y = 5x + 12.
(a) State the gradient of l₁.
(1)
The line l₂ is parallel to l₁ and passes through the point E (12... show full transcript
Worked Solution & Example Answer:Figure 2 shows the straight line l₁ with equation 4y = 5x + 12 - Edexcel - A-Level Maths Pure - Question 9 - 2018 - Paper 1
Step 1
State the gradient of l₁.
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Answer
To find the gradient of the line l₁ given by the equation 4y = 5x + 12, we first rewrite it in slope-intercept form (y = mx + b). Dividing all terms by 4 gives:
y = rac{5}{4}x + 3
Thus, the gradient of l₁ is ( \frac{5}{4} ).
Step 2
Find the equation of l₂.
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Answer
Since l₂ is parallel to l₁, it has the same gradient, which is ( \frac{5}{4} ). The line passes through the point E (12, 5). We can use the point-slope form to find the equation:
y−y1=m(x−x1)
Substituting the values, we have:
y−5=45(x−12)
Expanding this gives:
y−5=45x−15y=45x−10
Thus, the equation of l₂ is ( y = \frac{5}{4}x - 10 ).
Step 3
Find the coordinates of (i) the point B.
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Answer
The point B is where l₂ cuts the y-axis, which occurs when x = 0:
y=45(0)−10=−10
Therefore, the coordinates of point B are (0, -10).
Step 4
Find the coordinates of (ii) the point C.
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Answer
The point C is where l₂ cuts the x-axis, which occurs when y = 0:
0=45x−10
Rearranging gives us:
45x=10
Multiplying through by ( \frac{4}{5} ) yields:
x=8
Therefore, the coordinates of point C are (8, 0).
Step 5
Find the area of ABCD.
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Answer
To find the area of parallelogram ABCD, we can use the formula for area:
Area=base×height
The base (length of AB) can be determined as the distance from A (0, 3) to B (0, -10), which is:
3−(−10)=3+10=13
The height corresponds to the distance from C (8, 0) to the y-axis. Thus, it is 8 units.