All SAT Math Resources
Example Questions
Example Question #1 : How To Find The Equation Of A Parallel Line
There is a line defined by the equation below:
There is a second line that passes through the point and is parallel to the line given above. What is the equation of this second line?
Parallel lines have the same slope. Solve for the slope in the first line by converting the equation to slope-intercept form.
3x + 4y = 12
4y = –3x + 12
y = –(3/4)x + 3
slope = –3/4
We know that the second line will also have a slope of –3/4, and we are given the point (1,2). We can set up an equation in slope-intercept form and use these values to solve for the y-intercept.
y = mx + b
2 = –3/4(1) + b
2 = –3/4 + b
b = 2 + 3/4 = 2.75
Plug the y-intercept back into the equation to get our final answer.
y = –(3/4)x + 2.75
Example Question #2 : How To Find The Equation Of A Parallel Line
What is the equation of a line that is parallel to and passes through ?
To solve, we will need to find the slope of the line. We know that it is parallel to the line given by the equation, meaning that the two lines will have equal slopes. Find the slope of the given line by converting the equation to slope-intercept form.
The slope of the line will be . In slope intercept-form, we know that the line will be . Now we can use the given point to find the y-intercept.
The final equation for the line will be .
Example Question #3 : Parallel Lines
What line is parallel to and passes through the point ?
Start by converting the original equation to slop-intercept form.
The slope of this line is . A parallel line will have the same slope. Now that we know the slope of our new line, we can use slope-intercept form and the given point to solve for the y-intercept.
Plug the y-intercept into the slope-intercept equation to get the final answer.
Example Question #1 : Parallel Lines
What is the equation of a line that is parallel to the line and includes the point ?
The line parallel to must have a slope of , giving us the equation . To solve for b, we can substitute the values for y and x.
Therefore, the equation of the line is .
Example Question #4 : Parallel Lines
What line is parallel to , and passes through the point ?
Converting the given line to slope-intercept form we get the following equation:
For parallel lines, the slopes must be equal, so the slope of the new line must also be . We can plug the new slope and the given point into the slope-intercept form to solve for the y-intercept of the new line.
Use the y-intercept in the slope-intercept equation to find the final answer.
Example Question #2 : Parallel Lines
What line is parallel to at ?
None of the answers are correct
Find the slope of the given line: (slope intercept form)
therefore the slope is
Parallel lines have the same slope, so now we need to find the equation of a line with slope and going through point by substituting values into the point-slope formula.
So,
Thus, the new equation is
Example Question #1 : Parallel Lines
If the line through the points (5, –3) and (–2, p) is parallel to the line y = –2x – 3, what is the value of p ?
0
–10
4
–17
11
11
Since the lines are parallel, the slopes must be the same. Therefore, (p+3) divided by (–2–5) must equal –2. 11 is the only choice that makes that equation true. This can be solved by setting up the equation and solving for p, or by plugging in the other answer choices for p.
Example Question #5 : How To Find The Equation Of A Parallel Line
Which of these formulas could be a formula for a line perpendicular to the line ?
This is a two-step problem. First, the slope of the original line needs to be found. The slope will be represented by "" when the line is in -intercept form .
So the slope of the original line is . A line with perpendicular slope will have a slope that is the inverse reciprocal of the original. So in this case, the slope would be . The second step is finding which line will give you that slope. For the correct answer, we find the following:
So, the slope is , and this line is perpendicular to the original.
Example Question #392 : Geometry
Which of the following equations is parallel to: and goes through the point ?
Step 1: We need to define what a parallel line is. A parallel line has the same slope as the line given in the problem. Parallel lines never intersect, which tells us that the y-intercepts of the two equations are different.
Step 2: We need to identify the slope of the line given to us. The slope is always located in front of the .
The slope in the equation is .
Step 3: If we said that a parallel line has the same slope as the given line in the equation, the slope of the parallel equation is also .
Step 4. We need to write the equation of the parallel line in slope-intercept form:. We need to write b for the intercept because it has changed.
The equation is:
Step 5: We will use the point where and . We need to substitute these values of x and y into the equation in step 4 and find the value of b.
The numbers in red will cancel out when I multiply.
To find b, subtract 2 to the other side
Step 6: We put all of the parts together and make the final equation of the parallel line:
The final equation is:
Example Question #391 : Sat Mathematics
Consider line c to be y= -4x - 7. Which is the reflection of line c across the x-axis?
y = –4x + 7
y = 4x – 7
y = 4x + 7
y = (1/4)x + 7
y = 4x + 7
A line reflected across the x-axis will have the negative value of the slope and intercept. This leaves y= 4x + 7.