Sketch the graph of
y = 4 - |2x - 6|
Solve the inequality
Solve the inequality
4 - |2x - 6| > 2 - AQA - A-Level Maths Pure - Question 4 - 2020 - Paper 1
Question 4
Sketch the graph of
y = 4 - |2x - 6|
Solve the inequality
Solve the inequality
4 - |2x - 6| > 2
Worked Solution & Example Answer:Sketch the graph of
y = 4 - |2x - 6|
Solve the inequality
Solve the inequality
4 - |2x - 6| > 2 - AQA - A-Level Maths Pure - Question 4 - 2020 - Paper 1
Step 1
Sketch the graph of y = 4 - |2x - 6|
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Answer
To sketch the graph of the function, we need to determine the critical points and the overall shape of the graph. This function will produce an inverted V shape due to the absolute value.
Find the vertex: Set the expression inside the absolute value to zero to find the vertex.
0=2x−6
2x=6
x=3
We substitute x=3 into the function:
y=4−∣2(3)−6∣=4−∣0∣=4
Hence, the vertex is at (3, 4).
Find x-intercepts: Set y = 0:
0=4−∣2x−6∣
∣2x−6∣=4
This gives two cases:
Case 1: 2x−6=4 leads to 2x=10 or x=5.
Case 2: 2x−6=−4 leads to 2x=2 or x=1.
Thus, the x-intercepts are at (1, 0) and (5, 0).
Y-intercept: Set x=0:
y=4−∣2(0)−6∣=4−∣−6∣=4−6=−2.
So the y-intercept is at (0, -2).
The graph will have an inverted V shape pointing downwards, intersecting the y-axis at (0, -2), and the x-axis at (1, 0) and (5, 0), with the vertex at (3, 4). Labels for these points should be included on the graph.
Step 2
Solve the inequality
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Answer
To solve the inequality
4−∣2x−6∣>2:
Isolate the absolute value:
4−2>∣2x−6∣
2>∣2x−6∣
Set up two inequalities based on the definition of absolute value:
Case 1: 2x−6<2 leads to 2x<8 or x<4.
Case 2: −(2x−6)<2 leads to 2x−6<2 or 2x<8, which simplifies to the same inequality x<4.
Combine these with the other part derived from the absolute value inequality:
2x−6>−2 leads to 2x>4 or x>2.
Final solution: Therefore, combining both inequalities gives: