Answer:
Step-by-step explanation:
You want to find the equation for a line that passes through the two points:
(-2,5) and (5,-2).
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, (-2,5), point #1, so the x and y numbers given will be called x1 and y1. Or, x1=-2 and y1=5.
Also, let's call the second point you gave, (5,-2), point #2, so the x and y numbers here will be called x2 and y2. Or, x2=5 and y2=-2.
Now, just plug the numbers into the formula for m above, like this:
m=
-2 - 5
5 - -2
or...
m=
-7
7
or...
m=-1
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=-1x+b
Now, what about b, the y-intercept?
To find b, think about what your (x,y) points mean:
(-2,5). When x of the line is -2, y of the line must be 5.
(5,-2). When x of the line is 5, y of the line must be -2.
Because you said the line passes through each one of these two points, right?
Now, look at our line's equation so far: y=-1x+b. b is what we want, the -1 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 (-2,5) and (5,-2).
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:
(-2,5). y=mx+b or 5=-1 × -2+b, or solving for b: b=5-(-1)(-2). b=3.
(5,-2). y=mx+b or -2=-1 × 5+b, or solving for b: b=-2-(-1)(5). b=3.
See! In both cases we got the same value for b. And this completes our problem.
