MATH110 December 2014
• Q1 (a) • Q1 (b) • Q1 (c) • Q1 (d) • Q2 (a) • Q2 (b) • Q2 (c) • Q3 (a) • Q3 (b) • Q3 (c) • Q3 (d) • Q3 (e) • Q4 (a) • Q4 (b) • Q4 (c) • Q5 (a) • Q5 (b) • Q5 (c) • Q6 (a) • Q6 (b) • Q6 (c) • Q7 (a) • Q7 (b) • Q7 (c) • Q8 (a) • Q8 (b) • Q8 (c) • Q9 (a) • Q9 (b) • Q10 • Q11 •
Question 06 (b)
This question has three independent parts.
(b) Find all points where the function crosses the -axis.
Make sure you understand the problem fully: What is the question asking you to do? Are there specific conditions or constraints that you should take note of? How will you know if your answer is correct from your work only? Can you rephrase the question in your own words in a way that makes sense to you?
If you are stuck, check the hint below. Consider it for a while. Does it give you a new idea on how to approach the problem? If so, try it!
Find the points satisfying .
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Note that at the point where the graph crosses -axis, .
Therefore, it is enough to find points satisfying .
Since , we have
By drawing the graph of on the interval , we can easily observe that
at and .
Using the periodicity of , we get
for any or where . i.e., , where .
To sum, the points satisfying are .