5) \( \left(\frac{1}{3}\right)^{x}=3 \)

Determine the value of \( C \) that makes each expression a Perfect square. \( x^{2}+14+c \)

Expand. Your answer should be a polynomial in standard form. \( (6 f-7)(8 f-9)=\square \)

Expand. Your answer should be a polynomial in standard form. \( (-f+10)(3 f-1)=\square \)

6. Al resolver el sistema \( \left\{\begin{array}{l}5 x+6 y=20 \\ 4 x-3 y=-23\end{array}\right. \) \( \begin{array}{rlrl}5 x . x=2 & \text { b. } x=-2 & \text { c. } x=5 & \text { d. } x=-5 \\ y=5 & y=5 & y=-2 & y=2\end{array} \)

What is a proportional relationship?