C) (7, 8)
D) (8, 7)
Ways to Remember
Having trouble
remembering that the
x-coordinate comes
before the y-coordinate
in an ordered pair? Just
remember the phrase “x
before y, walk before you
fly.” The letter x comes
before y in the dictionary.Here’s How to Crack It
Plug in the answers, starting with (B). The (x, y) point is (7, 7), so plug in 7 for x and 7 for y. The
equation becomes 7 = 2(7) – 6 or 7 = 8. This isn’t true, so eliminate (B). The result was very close to a
true statement, and the point in (C) has the same x-coordinate and a larger y-coordinate, so try that next.
Because 8 = 2(7) – 6, (C) is the correct answer.
Slope
You always read a graph from left to right. As you read the graph, how much the line goes up or down is
known as the slope. Slope is the rate of change of a line and is commonly known as “rise over run.” It’s
denoted by the letter m. Essentially, it’s the change in the y-coordinates over the change in x-coordinates
and can be found with the following formula:
m = This formula uses the points (x 1 , y 1 ) and (x 2 , y 2 ).
Let’s do an example. If you have the points (2, 3) and (7, 4), the slope of the line created by these points
would be
m = So the slope of a line with points (2, 3) and (7, 4) would be , which means that every time you go up 1
unit, you travel to the right 5 units.
Equation of a Line—Slope-Intercept Form
The equation of a line can take multiple forms. The most common of these is known as the slope-intercept
form. If you know the slope and the y-intercept, you can create the equation of a given line. A slope-