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Write an equation for the graph shown in the form y=ax+b.

I know I have to use the y=mx+b equation but I don't know how

 

 Oct 30, 2022
 #1
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m is the slope of the line.  That's the distance it goes vertically divided by the distance it goes horizontally. 

 

In this case, using known points, the vertical distance is        (+2) – (0)   =   +2  

In this case, using known points, the horizontal distance is    (+5) – (–5)  =  +10  

 

So the slope, which is conventionally called "m" is 0.2  

 

b is the y-intercept of the line.  That the point where the line crosses the y-axis.  

Looking at the graph, it appears that the y-intercept is at (0,1)  

 

So the y-intercept, which is conventionally called "b" is 1. 

 

Plugging the values into y = mx + b, we find the equation to be  y = 0.2x + 1   tentatively  

 

 

Sometimes it isn't as straightforward, so plug in those two known values of x to see if it works. 

 

When x = –5,  does y = 0.2x + 1 equal 0 ?     (0.2 • –5) + 1  =  (–1) + (+1)  =  0  so yes  

When x = +5,  does y = 0.2x + 1 equal 2 ?     (0.2 • +5) + 1  =  (+1) + (+1)  =  2  so yes  

.

 Oct 30, 2022
 #2
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So how could I do it if I was given a equation to graph?

 

or when its asking write a equation that intersects with this point?

 Oct 30, 2022

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