a. Add \( 4 \sqrt{5}+\sqrt{5} \). b. Multiply \( 4 \sqrt{5} \cdot \sqrt{5} \). c. Describe the differences in parts (a) and (b).

2. If \( \frac{a}{x}+1=\frac{c}{r} \), which is an expression for \( x \) in terms of \( c \) and \( a \) ? \( \begin{array}{lll}\text { A. } x=c+a & \text { B. } x=c-a & \text { C. } x=a-c\end{array} \) D. \( x=a+c+1 \)

sif \( a=1, b=2 \) and \( c=-1 \) \( 6 a^{2} c-4 b^{2} c-3 c^{2} a-b c-c^{2}-2 b^{2} c-a^{2} c \)

5o. \( x^{2}-y^{2}+2 x+1 \)

Divide and state the quotient in simplest form. \( \frac{72 y}{y^{2}-9} \div \frac{48 y}{y^{2}-6 y+9} \) \( \frac{3\left(y^{2}-6 y+9\right)}{2\left(y^{2}-9\right)} \) \( \frac{2 y+6}{3 y-9} \) \( \frac{3}{2} \) \( \frac{3 y-9}{2 y+6} \)

\( x^{2}-2 x-15-15 \) 2. Simplify: \( 4(2 x+1)-3(x-5) \)