Example

Mini Lecture
Factor completely.

1. $$x^2-81$$

2. $$x^2+49$$

3. $$x^3-x^2$$

4. $$27-r^3$$

5. $$12x^2-11x+2$$

6. $$100x^2-100x-600$$

7. $$x^3+5x^2-9x-45$$

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