McGraw-Hill Education GRE 2019

Y-intercept

In the equation y = mx + b, b refers to the y-intercept of the line. The y-intercept of

a line refers to where a line crosses the y-axis. Since this point is on the y-axis, the

x-coordinate will always be zero.

y

x

y-intercept = 2

(0, 2)

Points and the Equation for a Line

Once you know the slope and y-intercept of a line, you can substitute those

values into the equation for the line. For example, if you are told that a line has a

y-intercept of 3 and a slope of 7, plug in 3 for b and 7 for m: y = 7x + 3.

Sometimes, the GRE will define a line using a different form than the previous

one. Always manipulate the equation to be in y = mx + b form.

If the equation for line k is 2x + 3y = 6, what is the slope of line k?

SOLUTION: Isolate y so that the equation is in y = mx + b form. Subtract 2x:

2 x + 3y = 6

− 2x − 2x

3 y = −2x + 6

Divide both sides by 3:

3 y = −2x + 6

3 3

y = −^23 x + 2

The slope of the line is −^23.

CHAPTER 13 ■ GEOMETRY 433

04-GRE-Test-2018_313-462.indd 433 12/05/17 12:06 pm