1. Simplify the following expressions:
   1. $(\frac{7}{9})^0$
   2. $y^{-2}y^{-5}$
   3. $(-xy^2)^{-4}$
   4. $(y^3y^4)^4$
   5. $y^2y^5$
2. Bacteria grow by doubling every 10 minutes. Suppose you are infected by one bacteria, and allow it to grow for 4 hours. Then you begin frantically washing and ...

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