standard_description: Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
problem_activity: Task
Consider the algebraic expressions below:
$$ (n + 2)^2 - 4 \qquad \text{and} \qquad n^2 + 4n. $$
Use the figures below to illustrate why the expressions are equivalent:
[IMG]
Find some ways to algebraically verify the same result.


aligns: no