Question 8 Simplify the expression \( \left(5 m^{2} n^{7}\right)^{3} \). Explain how you solved the problem and justify each step by naming the appropriate property. (i) Instructions

Solve for \( r \). \( 3^{r}+3^{3-r}=28 \)

If \( f(x)=\left\{\begin{array}{ll}2 x-5 & \text { if }-2 \leq x \leq 4 \\ x^{3}-4 & \text { if } 4<x \leq 5\end{array}\right. \), find: (a) \( f(0) \), (b) \( f(1),(c) f(4) \), and \( (d) f(5) \). (a) \( f(0)=\square \) (b) \( f(1)=\square \) (c) \( f(4)=\square \) (d) \( f(5)=\square \)

10. The perimeter of a rectangular plot of land is 72 meters and its area is \( 308 \mathrm{~m}^{2} \). What are the dimensions of the property?

Write the function whose graph is the graph of \( y=(x+4)^{2} \), but is reflected about the \( x \)-axis. \( y=\square \) (Simplify your answer.)

9. Use any method to solve the system: \( \left\{\begin{array}{c}x^{2}+y^{2}=9 \\ 9 x^{2}+4 y^{2}=36\end{array}\right. \)