11. Solve for \( x: \quad x^{2}-2 x=15 \quad \) Circle the best answer. \( \begin{array}{l}\text { a. } x=-2 \\ \text { b. } x=-3 \\ \text { c. } x=-5 \text { or } x=5 \\ \text { d. } x=-3 \text { or } x=5 \\ \text { e. } x=-5 \text { or } x=-3 \\ \text { f. } x=-2 \text { or } x=5\end{array} \)

Complete the square to write \( y=2 x^{2}+12 x-7 \) in graphing form. Then determine the vertex and the intercepts of the parabola. 1

Simplify he following fully: \( \frac{3^{3+1}-3^{-1}}{23^{x}} \) \( \frac{3^{x} \cdot 3^{1}-3^{x} \cdot 3^{-1}}{2 \cdot 3^{x}} \frac{3^{x}\left(1-\frac{1}{3}\right)}{23^{x}} \)

How much pure acid should be mixed with 2 gallons of a \( 50 \% \) acid solution to get an \( 80 \% \) acid solution?

15 It is given that \( t=\frac{b^{2}-4}{3-b^{2}} \). Express \( b \) in terms of \( t \)

QUESTION 12 If \( 2^{x} 5^{y}=16 \times 125 \), where \( x \) and \( y \) are positive integers, determine \( x-y \) :