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Example Questions
Example Question #1 : How To Find The Equation Of A Line
Which of the following is the equation of a line between the points and
?
Since you have y-intercept, this is very easy. You merely need to find the slope. Then you can use the form to find one version of the line.
The slope is:
Thus, for the points and
, it is:
Thus, one form of our line is:
If you move the to the left side, you get:
, which is one of your options.
Example Question #2 : How To Find The Equation Of A Line
What is an equation of the line going through points and
?
If you have two points, you can always use the point-slope form of a line to find your equation. Recall that this is:
You first need to find the slope, though. Recall that this is:
For the points and
, it is:
Thus, you can write the equation using either point:
Now, notice that one of the options is:
This is merely a multiple of the equation we found, so it is fine!
Example Question #3 : How To Find The Equation Of A Line
Given the graph of the line below, find the equation of the line.
To solve this question, you could use two points such as (1.2,0) and (0,-4) to calculate the slope which is 10/3 and then read the y-intercept off the graph, which is -4.
Example Question #4 : How To Find The Equation Of A Line
Which line passes through the points (0, 6) and (4, 0)?
y = 2/3 + 5
y = 2/3x –6
y = 1/5x + 3
y = –3/2 – 3
y = –3/2x + 6
y = –3/2x + 6
P1 (0, 6) and P2 (4, 0)
First, calculate the slope: m = rise ÷ run = (y2 – y1)/(x2 – x1), so m = –3/2
Second, plug the slope and one point into the slope-intercept formula:
y = mx + b, so 0 = –3/2(4) + b and b = 6
Thus, y = –3/2x + 6
Example Question #741 : Act Math
Let W and Z be the points of intersection between the parabola whose graph is y = –x² – 2x + 3, and the line whose equation is y = x – 7. What is the length of the line segment WZ?
7√2
4
4√2
7
7√2
First, set the two equations equal to one another.
–x² – 2x + 3 = x – 7
Rearranging gives
x² + 3x – 10 = 0
Factoring gives
(x + 5)(x – 2) = 0
The points of intersection are therefore W(–5, –12) and Z(2, –5)
Using the distance formula gives 7√2
Example Question #742 : Act Math
In an xy-plane, what is the length of a line connecting points at (–2,–3) and (5,6)?
9.3
7.5
12.5
11.4
11.4
Use the distance formula:
D = √((y2 – y1)2 + (x2 – x1)2)
D = √((6 + 3)2 + (5 + 2)2)
D = √((9)2 + (7)2)
D = √(81 + 49)
D = √130
D = 11.4
Example Question #743 : Act Math
What is the distance between points and
, to the nearest tenth?
The distance between points and
is 6.4. Point
is at
. Point
is at
. Putting these points into the distance formula, we have
.
Example Question #2 : How To Find The Length Of A Line With Distance Formula
What is the slope of the line between points and
?
The slope of the line between points and
is
. Point
is at
. Point
is at
. Putting these points into the slope formula, we have
.
Example Question #744 : Act Math
What is the distance between and
?
Let and
and use the distance formula:
. The distance formula is a specific application of the more general Pythagorean Theorem:
.
Example Question #745 : Act Math
What is the distance, in coordinate units, between the points and
in the standard
coordinate plane?
The distance formula is , where
= distance.
Plugging in our values, we get
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