SSAT Upper Level Quantitative › How to find the equation of a line
Let y = 3_x_ – 6.
At what point does the line above intersect the following:
They do not intersect
They intersect at all points
(0,–1)
(–5,6)
(–3,–3)
If we rearrange the second equation it is the same as the first equation. They are the same line.
Find the equation of the line that has a slope of and passes through the point
.
In finding the equation of the line given its slope and a point through which it passes, we can use the slope-intercept form of the equation of a line:
, where
is the slope of the line and
is its
-intercept.
Since the problem gives us the slope of the line , we just need to use the point that is given to us to find the
-intercept. Plug in known values for
and
taken from the given point into the
equation and solve for
to find the
-intercept:
Multiply:
Add to each side of the equation:
Now, we can write the final equation by plugging in the given slope and the
-intercept
:
Find the equation of the line that has a slope of and passes through the point
.
In finding the equation of the line given its slope and a point through which it passes, we can use the slope-intercept form of the equation of a line:
, where
is the slope of the line and
is its
-intercept.
Since the problem gives us the slope of the line , we just need to use the point that is given to us to find the
-intercept. Plug in known values for
and
taken from the given point into the
equation and solve for
to find the
-intercept:
Multiply:
Subtract from each side of the equation:
Now, we can write the final equation by plugging in the given slope and the
-intercept
:
Find the equation of a line that has a slope of and passes through the point
.
The question gives us both the slope and the -intercept of the line. Remember that
represents the slope, and
represents the
-intercept to write the following equation:
Alternatively, if you did not realize that the problem gives you the -intercept, you could solve it by using the slope-intercept form of the equation of a line:
, where
is the slope of the line and
is its
-intercept.
Since the problem gives us the slope of the line , we would just need to use the point that is given to us to find the
-intercept. We could plug in the known values for
and
taken from the given point into the
equation and solve for
to find the
-intercept:
Multiplying leaves us with:
.
We could then substitute in the given slope and the -intercept into the
equation to arrive at the correct answer:
What line goes through the points (1, 3) and (3, 6)?
3x + 5y = 2
2x – 3y = 5
4x – 5y = 4
–3x + 2y = 3
–2x + 2y = 3
If P1(1, 3) and P2(3, 6), then calculate the slope by m = rise/run = (y2 – y1)/(x2 – x1) = 3/2
Use the slope and one point to calculate the intercept using y = mx + b
Then convert the slope-intercept form into standard form.
Find the equation of the line that has a slope of and passes through the point
.
The question gives us both the slope and the -intercept of the line, allowing us to write the following equation by inserting those values into the slope-intercept form of the equation of a line,
:
Alternatively, if you did not realize that the problem gives you the -intercept, you could solve it by using the slope-intercept form of the equation of a line. Since the problem gives us the slope of the line
, we would just need to use the point that is given to us to find the
-intercept. We could plug in the known values for
and
taken from the given point into the
equation and solve for
to find the
-intercept:
Multiplying leaves us with:
We could then substitute in the given slope and the -intercept into the
equation to arrive at the correct answer:
Find the equation of the line that passes through the points and
.
First, notice that our -intercept for this line is
; we can tell this because one of the points,
, is on the
-axis since it has a value of
for
.
Now, we need to find the slope of the line. We can do that by using the slope equation:
We can substitute in the values of the provided points—,
,
and
—and then solve for the slope of the line that connects them:
Now, put the two pieces of information together and substitute them into the equation to solve the problem:
Find the equation of the line that passes through and
.
First, notice that our -intercept for this line is
; we can tell this because one of the points,
, is on the
-axis since it has a value of
for
.
Now, we need to find the slope of the line. We can do that by using the slope equation:
We can substitute in the values of the provided points—,
,
and
—and then solve for the slope of the line that connects them:
Now, put the two pieces of information together and substitute them into the equation to solve the problem:
Find the equation of a line that has a slope of and passes through the points
.
In finding the equation of the line given its slope and a point through which it passes, we can use the slope-intercept form of the equation of a line:
, where
is the slope of the line and
is its
-intercept.
Since the problem gives us the slope of the line , we just need to use the point that is given to us to find the
-intercept. Plug in known values for
and
taken from the given point into the
equation to find the
-intercept:
Multiply:
Subtract from each side of the equation:
Now that you've solved for , you can plug the given slope
and the
-intercept
into the slope-intercept form of the equation of a line to figure out the answer:
Find the equation of the line that passes through the points .
First, notice that our -intercept for this line is
; we can tell this because one of the points,
, is on the
-axis since it has a value of
for
.
Now, we need to find the slope of the line. We can do that by using the slope equation:
We can substitute in the values of the provided points—,
,
and
—and then solve for the slope of the line that connects them:
Now, put the two pieces of information together and substitute them into the equation to solve the problem: