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7 votes
Write an equation for the function that includes the points (2, 100) and (3, 1000)

User Eduard Jacko
by
2.3k points

1 Answer

6 votes
6 votes

Answer:

y=900x-1700

Explanation:

(sorry if the explanation is long)

First of all, remember what the equation of a line is:

y = mx+b

Where:

m is the slope, and

b is the y-intercept

First, let's find what m is, the slope of the line...

The slope of a line is a measure of how fast the line "goes up" or "goes down". A large slope means the line goes up or down really fast (a very steep line). Small slopes means the line isn't very steep. A slope of zero means the line has no steepness at all; it is perfectly horizontal.

For lines like these, the slope is always defined as "the change in y over the change in x" or, in equation form:

So what we need now are the two points you gave that the line passes through. Let's call the first point you gave, (2,100), point #1, so the x and y numbers given will be called x1 and y1. Or, x1=2 and y1=100.

Also, let's call the second point you gave, (3,1000), point #2, so the x and y numbers here will be called x2 and y2. Or, x2=3 and y2=1000.

Now, just plug the numbers into the formula for m above, like this:

m=

1000 - 100

3 - 2

or...

m=

900

1

or...

m=900

So, we have the first piece to finding the equation of this line, and we can fill it into y=mx+b like this:

y=900x+b

Now, what about b, the y-intercept?

To find b, think about what your (x,y) points mean:

(2,100). When x of the line is 2, y of the line must be 100.

(3,1000). When x of the line is 3, y of the line must be 1000.

Because you said the line passes through each one of these two points, right?

Now, look at our line's equation so far: y=900x+b. b is what we want, the 900 is already set and x and y are just two "free variables" sitting there. We can plug anything we want in for x and y here, but we want the equation for the line that specfically passes through the two points (2,100) and (3,1000).

So, why not plug in for x and y from one of our (x,y) points that we know the line passes through? This will allow us to solve for b for the particular line that passes through the two points you gave!.

You can use either (x,y) point you want..the answer will be the same:

(2,100). y=mx+b or 100=900 × 2+b, or solving for b: b=100-(900)(2). b=-1700.

(3,1000). y=mx+b or 1000=900 × 3+b, or solving for b: b=1000-(900)(3). b=-1700.

See! In both cases we got the same value for b. And this completes our problem.

The equation of the line that passes through the points

(2,100) and (3,1000)

is

y=900x-1700

User Andrew Paes
by
3.3k points