Solving Equations with Modulus Functions (Edexcel A Level Maths): Revision Note
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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
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How do I solve modulus equations?
STEP 1 Sketch the graphs including any modulus (reflected) parts
(see Modulus Functions – Sketching Graphs)
STEP 2 Locate the graph intersections
STEP 3 Solve the appropriate equation(s) or inequality
For
the two possible equations are
and
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Examiner Tips and Tricks
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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