Why does my child think (x + 3)² = x² + 9?
Your child squares each term to square a bracket, such as (x + 3)² = x² + 9.
Why children do it
Squaring each part looks like the natural way to square a bracket. But (x + 3)² means (x + 3)(x + 3), and multiplying every pair gives a middle term too: x² + 3x + 3x + 9, which is x² + 6x + 9.
How to help at home
Ask them to write the bracket out twice, (x + 3)(x + 3), and multiply every pair.
The right way
Expand: (x + 3)²
- (x + 3)(x + 3)Squaring means multiplying by itself.
- x² + 3x + 3x + 9Multiply every term by every term.
- x² + 6x + 9Collect the x terms.
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