9 . D
Use the distance formula to calculate the lengths between each pair of points. The
perimeter of the triangle is the sum of these lengths.
10 . E
g(f(x)) is a compound function. Since f(x) = x + 4, g(f(x)) = 6 – (x + 4)^2
Once you have figured out the compound function, you answer this question with the help
of a graphing calculator, which will indicate the highest point of the graph.
Alternatively, you can find the maximum of the function by first finding the minimum value
of the squared binomial. (x + 4)^2 has a minimum value of zero, since a square never has a
value less than 0. Six minus 0 equals 6, and that is the maximum value of the function g(f(x)),
which occurs when x = −4. For any value of x other than −4, (x + 4)^2 will be greater than 0, so
the function will have a value less than 6.
11 . C