Problem / Question
Introduction
This
question was from a Facebook group not dedicated to “Singapore math”. The thing is, mathematics is really
an international experience, especially with modern social media.
Simultaneous equations can pose a challenge to students, but this one is
absolutely more challenging, because of the absolute
value.
The Absolute Value
Strategy
The problem
is: we do not know whether each of x
and y is negative or otherwise. That potentially raises complications. There seems to be 4 cases to check. However, by making assumptions [H08] separately and checking for contradictions [H07], we can narrow down the possibilities. [H10] Finally, we can simplify the problem to a
regular pair of simultaneous linear equations [H10] and solve it by the method of elimination. [H10, H11]
Solution
H04. Look for pattern(s) [deciding what to eliminate]
H07. Use guess and check [is x
negative? is y
negative?]
H08. Make suppositions [is
x negative? is y negative?]
H10. Simplify the problem
H11. Solve part of the problem
H13* Use Equation / write a
Mathematical Sentence
Suitable Levels
* Lower Secondary Olympiad
* GCE ‘O’ Level Additional Mathematics, “IP Mathematics”
(challenge)
* other syllabuses that involve simultaneous
equations and absolute values
* any precocious or independent learner who
wants his/her mind tickled
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