Complete the sentences with for or since. I haven't seen Carrie I've lived in the same house We haven't been back to Greece \( \square \) July, 2009 . It hasn't stopped raining \( \square \) three days. My dad's had the same mobile phone \( \square 2015 \) ! We've been on holiday \( \square \) six weeks now.

A. \( \left\{\begin{array}{c}-x+3 y=5 ; \text { Ecuactón } 1 \\ x+y=4 ; \text { Ecuacion } 2\end{array}\right. \)

Solve the equation. \[ -4(5 t-6 t)=2+10 \]

Solve the equation. \[ 2 x+7=2(x-12) \] The solution set is \( \square \). (Select "all real numbers" if applicable.) \( \begin{array}{cc}\{\square\} & \{\} \\ \begin{array}{c}\text { all real } \\ \text { numbers }\end{array} & \frac{\square}{\square}\end{array} \)

a. Find the derivative function \( f^{\prime} \) for the function \( f \). b. Determine an equation of the line tangent to the graph of \( f \) at \( (a, f(a)) \) for the given value of a. \( f(x)=\sqrt{3 x+4}, a=4 \) a. \( f^{\prime}(x)=\square \)

42. \( (5 x+2 y)^{2}-(3 x-7 y)^{2}= \) A) \( 2 x+9 y \) B) \( 16 x^{2}-45 y^{2} \) C) \( (8 x+5 y)(2 x+9 y) \) D) \( (8 x-5 y)(2 x+9 y) \)