These are two different types of max min problems but I understand that they go on a graph instead of being the usual rectangle with a given value question.
two lines are parrallel if they have the same slope. the slope of the line is 9. so we simply want to find the 's that make the tangent lines to the curve have a slope of 9. the derivative gives the formula for the slope of the tangent line.
Now we simply solve:
i leave that to you
http://www.mathhelpforum.com/math-he...ma-minima.html as a hint for the second
i assume you remember how to maximize a function
why did you think you would plug it into the line?