Test 7 Section 9 - #11 (page 798)

You can use your graphing calculator to help you visualize this (if you use a graphing calculator).  They tell you the slope of the line is -4/5, so you can graph a line with that slope simply by putting "y = (-4/5)x" in your calculator.  You can do the same with all the answer choices, and eyeball pretty easily which one is a true reflection across the x-axis.

Let's assume for a minute that you're doing this question without a graphing calculator, though.  A reflection across the x-axis negates the y-values of your graph.  How will that affect the slope?  Well, let's use the same equation I made up above to see:

2 easy points to find on that graph are (0,0), and (5,-4). If I reflect those two points across the x-axis, what happens?  (0,0) stays the same.  (5,-4) reflects to (5,4), because we're negating the -4, to get +4.  What's the slope of a line that goes through (0,0) and (5,4)?

(B) is our answer.

Test 7 Section 9 - #10 (page 797)

This is a PLUG-IN question. They're saying he put up n posters, but let's just say he wanted to put up 5.

 The question tells us he uses 4 6-inch pieces of tape to put up each poster (seems wasteful to me, but whatever). That's 24 inches of tape per poster, or 2 feet of tape per poster.  Remember, the question asks for answers in feet. So if he puts up 5, as we're plugging in for n, he's using 5x2 feet of tape, or 10 feet. If he started with 300 feet, he'll be left with 290 feet.

Now, go to the answer choices, and see which one gives you 290 when you plug 5 in for n:

(A) 300 - 6(5) = 270
(B) 300 - 2(5) = 290
(C) 300 - 5 = 295
(D) 300 - (1/2)(5) = 297.5
(E) 300 - (1/4)(5) = 298.75