Direct Proportion and The Straight Line Graph
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Straight line graphs that go through the origin, like the one immediately below, show that the quantities on the graph are in direct proportion. This graph states, therefore, that A is directly proportional to B. It also states that B is directly proportional to A, but we are going to work with the statement 'A is directly proportional to B'.
For the above graph:
This is how you write a direct proportion. The symbol in the middle is the Greek letter alpha.
It reads: A is directly proportional to B.
It means: By whatever factor A changes, B changes by the same factor.
So, let's look at the graph and see if by whatever factor A changes, B changes by the same factor.
This is what we are looking for, as we go from 'sub 1' to 'sub 2':
About the factor changes:
Below is an example of a point on this graph. The point is (B1, A1) and it has coordinates (1, 1).
For the above graph:
Coordinate for B1.
Coordinate for A1.
We will check for this shape of a graph if we change A by some factor, does B truly change by the same factor, thus showing that this straight line through the origin represents a direct proportion. In the graph below we change the quantity A by a factor of 3; that is, we triple it.
For the above graph:
Coordinates for (B1, A1).
Coordinates for (B2, A2).
Going from 'sub 1' to 'sub 2', A changes by a factor of 3. That is, A1 times a factor of 3 equals A2.
Going from 'sub 1' to 'sub 2', B also changes by a factor of 3. Likewise, B1 times a factor of 3 equals B2.
Both A and B change by the same factor. That factor is 3.
Therefore, A is directly proportional to B.
Again, the picture:
Let's try this below again for another point using the same graph. Here's the picture:
These steps show the factor changes:
For the above graph:
Coordinates for (B1, A1).
Coordinates for (B2, A2).
Going from 'sub 1' to 'sub 2', A changes by a factor of 4.
Going from 'sub 1' to 'sub 2', B also changes by a factor of 4.
Both A and B change by the same factor. That factor is 4.
Therefore, A is directly proportional to B.
Again:
This straight line graph really tells two stories. If you can say that A is directly proportional to B, then you can state that B is directly proportional to A. The above works out the same.
The function in the graph used here is:
Or, using formal function definition writing:
Lastly:
If someone says, 'A is proportional to B', they most assuredly mean, 'A is directly proportional to B'. Some might feel that the constant inclusion of the word 'direct' is unnecessary. It does, though, get to exactly what you are talking about, because there are other types of proportions
So it is asking you to group like term so
x terms can be grouped/added/subtracted to other x terms, but not to x^2 or x^3 terms
x^2 terms to x^2 and so on so
1. 9-3k+5k=
9+(5k-3k)=
9+2k
2. k^2+2k+4k=
k^2+(2k+4k)=
k^2+6k=
Answer:
The first one
Step-by-step explanation:
Answer:
Domain: {-6, -2, -1, 1, 3, 6}
Range: {-6, -2, -1, 0, 3}
Step-by-step explanation:
to find the domain of a function, you look at all the possible x-values. this means you look at all the points, and see what their x-values are.
for example, the first point on the left is at (-6, -1). this means that -6 is in the domain. continue doing this for all the points, and you get {-6, -2, -1, 1, 3, 6}
to find the range of a function, it's just like domain but with y-values.
for example, for the leftmost point, it's at (-6, -1) so -1 is part of the range. continuing this with all the points, you get {-6, -2, -1, 0, 3}
