Slope

Link of the Day

Write it Down! This infographic linked today from www.coolsiteoftheday.com discusses the importance of taking notes, a few different methods, and the potential benefits and drawbacks of taking notes digitally or the old--fashioned way. Did you know that your brain actually processes information differently while you're taking notes? This is a good resource to bookmark and revisit when you notice that your class notes are less than helpful--it might be time to try out a different method. 

5/15 Slope

Read the following SAT test question and then select the correct answer. 

Remember to read carefully, identify the bottom line, assess your options, attack the problem, and loop back. When you use this method, you will get more problems right and you will move faster through the test.

In the xy-plane, line l passes through the points (a, 0) and (0, 2a), where a > 1. What is the slope of line l?

First, read carefully. You have two points on a line, which means you can visualize that line if you wish. Picking a number for a might make that easier if the variable trips you up. Next, identify the bottom line. The question asks for the slope of line l, so at the top of your scratch work write "slope = ?"

Now assess your options. Since you need to find the slope of the line, a good place to start is with the formula for slope: rise over run. There are two choices here; you can use a as a variable or you can pick a number for a. Using a directly involves fewer steps because you don't need to plug in the value, but manipulating the variable can be confusing for some and can cost time. Which tool you choose to solve the problem is up to your personal preference.



Either way, the first step in the problem is to set up your formula. Since a must by greater than 1, I'll use 2.

                                                             

                                                                    

                                                                    

Now loop back to make sure that you answered the right question. Your bottom line asks for the slope, so you found the change in y-coordinates (rise) and the change in x-coordinates (run), divided one by the other and reduced. That is the slope, so -2 is the answer you need.

Look at the answer choices:

A) -2

B)

C) 2

D) -2a

E) 2a

The answer is A.


On sat.collegeboard.org, 42% of responses were correct.


For more help with math, visit www.myknowsys.com!