Here is a list of equations. Circle all the equations that are identities. Be prepared to
explain your reasoning.
1. a = -a
2. a² + 2ab + b² = (a + b)²
3. a² - 2ab + b² = (a - b)²
4. a²b² = (a - b)(a - b)
5. (a + b)(a²- ab + b²) = a³ - b³
6. (a - b)³=a³-b³-3ab(a + b)
7.a²(a - b)4-b²(a - b) = (a - b)²(a + b)