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Modulus Functions - Solving Equations (CIE A Level Maths: Pure 3)
Revision Note
Modulus Functions - Solving Equations
Modulus graphs and equations
- Two non-parallel straight-line graphs would intersect once
- If modulus involved there could be more than one intersection
- Deducing where these intersections are is crucial to solving equations
How do I solve modulus equations?
- STEP 1 Sketch the graphs including any modulus (reflected) parts
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- (see Modulus Functions – Sketching Graphs)
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- STEP 2 Locate the graph intersections
- STEP 3 Solve the appropriate equation(s) or inequality
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- For the two possible equations are and
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Examiner Tip
- Sketching the graphs is important as solving algebraically can lead to invalid solutions.
- For example, x = 1 is a solution to but it is not a solution to (substitute x = 1 into both sides and see why it does not work).
Worked example
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