12. Solve the following, giving your answers correct 2 decimal places. \( \begin{array}{ll}\text { (a) } 2 x^{2}-3 x-1=0 & \text { (b) } x^{2}-x-1=0 \\ \text { (c) } 3 x^{2}+2 x-4=0 & \text { (d) } x+3=\frac{7}{x}\end{array} \)

Solve the system of quadratic inequalities: \[ \begin{array}{c}\mathrm{y}>\mathrm{x}^{2}-1 \\ \mathrm{y} \leq-\frac{1}{3} \mathrm{x}^{2}+5\end{array} \]

The function \( f(x)=2 x^{2}-5 x+2 k-1 \) does not intersect the \( x- \) axis. Find the range of values of \( k \)

Which expression is equivalent to \(( x^ { \frac { 3} { 7} } ) ^ { 2} \) ?A. \(x^ { \frac { 6} { 14} } \)B. \(x^ { \frac { 17} { 7} } \)C. \(x^ { \frac { 6} { 7} } \)D. \(x^ { \frac { 5} { 7} } \)

Solve the system of quadratic inequalities: \[ y>x^{2}-1 \]

Find the points of intersection for the system \[ \begin{array}{l}\mathrm{y} \geq 2 \mathrm{x}^{2}+3 \mathrm{x}-20 \\ \mathrm{y} \leq \mathrm{x}^{2}+\mathrm{x}-5\end{array} \]