一个ll GRE Math Resources
Example Questions
Example Question #22 :Coordinate Geometry
There are two lines:
2x – 4y = 33
2x + 4y = 33
一个re these lines perpendicular, parallel, non-perpendicular intersecting, or the same lines?
Perpendicular
Non-perpendicular intersecting
Parallel
None of the other answers
The same
Non-perpendicular intersecting
To be totally clear, solve both lines in slope-intercept form:
2x – 4y = 33; –4y = 33 – 2x; y = –33/4 + 0.5x
2x + 4y = 33; 4y = 33 – 2x; y = 33/4 – 0.5x
These lines are definitely not the same. Nor are they parallel—their slopes differ. Likewise, they cannot be perpendicular (which would require not only opposite slope signs but also reciprocal slopes); therefore, they are non-perpendicular intersecting.
Example Question #211 :Geometry
Which of the above-listed lines are parallel?
and
一个ll four lines
,, and
and
None of them
,, and
There are several ways to solve this problem. You could solve all of the equations for. This would give you equations in the form. All of the lines with the samevalue would be parallel. Otherwise, you could figure out the ratio oftowhen both values are on the same side of the equation. This would suffice for determining the relationship between the two. We will take the first path, though, as this is most likely to be familiar to you.
Let's solve each for:
Here, you need to be a bit more manipulative with your equation. Multiply the numerator and denominator of thevalue by:
Therefore,,, andall have slopes of
例子问题# 212:Geometry
Which of the following is parallel to the line passing throughand?
Now, notice that the slope of the line that you have been given is. You know this because slope is merely:
However, for your points, there is no rise at all. You do not even need to compute the value. You know it will be. All lines with slopeare of the form, whereis the value thathas for allpoints. Based on our data, this is, foris always—no matter what is the value for. So, the parallel answer choice is, as both have slopes of.
Example Question #213 :Geometry
Which of the following is parallel to?
The line between the pointsand
The line between the pointsand
The line between the pointsand
The line between the pointsand
The line between the pointsand
The line between the pointsand
To begin, solve your equation for. This will put it into slope-intercept form, which will easily make the slope apparent. (Remember, slope-intercept form is, whereis the slope.)
Divide both sides byand you get:
Therefore, the slope is. Now, you need to test your points to see which set of points has a slope of. Remember, for two pointsand, you find the slope by using the equation:
For our question, the pairandgives us a slope of:
Example Question #11 :How To Find Out If Lines Are Parallel
Which of the following lines is parallel to:
First write the equation in slope intercept form. Addto both sides to get. Now divide both sides byto get. The slope of this line is, so any line that also has a slope ofwould be parallel to it. The correct answer is.
Example Question #1 :How To Find Out If Lines Are Parallel
Which pair of linear equations represent parallel lines?
Parallel lines will always have equal slopes. The slope can be found quickly by observing the equation in slope-intercept form and seeing which number falls in the "" spot in the linear equation,
We are looking for an answer choice in which both equations have the samevalue. Both lines in the correct answer have a slope of 2, therefore they are parallel.
Example Question #2 :How To Find Out If Lines Are Parallel
Which of the following equations represents a line that is parallel to the line represented by the equation?
Lines are parallel when their slopes are the same.
First, we need to place the given equation in the slope-intercept form.
Because the given line has the slope of, the line parallel to it must also have the same slope.