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Mathematics 8 Online
OpenStudy (pinklion23):

Help :) medal will be rewarded

OpenStudy (pinklion23):

OpenStudy (pinklion23):

hello :)

OpenStudy (trwatkins1):

hi

OpenStudy (trwatkins1):

do you know what numbers it goes through

OpenStudy (pinklion23):

well -4,1 is one of them

OpenStudy (pinklion23):

and hold on....

OpenStudy (pinklion23):

and 4,-1

OpenStudy (pinklion23):

and 0,0 of course

OpenStudy (trwatkins1):

its a

OpenStudy (pinklion23):

ok thx do you think you can help me with more?

OpenStudy (trwatkins1):

You want to find the equation for a line that passes through the two points: (-1,4) and (,). 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, (-1,4), point #1, so the x and y numbers given will be called x1 and y1. Or, x1=-1 and y1=4. Also, let's call the second point you gave, (,), point #2, so the x and y numbers here will be called x2 and y2. Or, x2= and y2=. Now, just plug the numbers into the formula for m above, like this: m= - 4 - -1 or... m= -4 1 or... m=-4 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=-4x+b Now, what about b, the y-intercept? To find b, think about what your (x,y) points mean: (-1,4). When x of the line is -1, y of the line must be 4. (,). When x of the line is , y of the line must be . Because you said the line passes through each one of these two points, right? Now, look at our line's equation so far: y=-4x+b. b is what we want, the -4 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 (-1,4) and (,). 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: (-1,4). y=mx+b or 4=-4 × -1+b, or solving for b: b=4-(-4)(-1). b=0. (,). y=mx+b or =-4 × +b, or solving for b: b=-(-4)(). b=0. 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 (-1,4) and (,) is y=-4x Notes: b came out to be zero, so there is no "+b" term.

OpenStudy (pinklion23):

copy and paste lol :)

OpenStudy (trwatkins1):

yea but sure i can try

OpenStudy (pinklion23):

thx

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