Why does my child think (6x + 9)/3 = 2x + 9?
Your child divides only part of the top of a fraction, such as (6x + 9)/3 as 2x + 9 instead of 2x + 3.
Why children do it
Cancelling looks like crossing out one thing on top and one on the bottom, so children divide the first term and stop. But the line under the top divides all of it: (6x + 9)/3 is 6x/3 + 9/3, which is 2x + 3. Only a factor of the whole top can be cancelled.
How to help at home
Ask them to split the fraction up: (6x + 9)/3 is 6x/3 + 9/3. Every part of the top is divided.
The right way
Simplify: (6x + 9)/3
- 6x/3 + 9/3Divide every part of the top by 3, not just the first.
- 2x + 36x ÷ 3 and 9 ÷ 3.
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