Point slope form: can't figure out example in index

bananagirl5

New member
Joined
Aug 1, 2007
Messages
2
On the example in the index for point slope form they give you a graph with points (-1,0) and they plotted the points. What i don't understand is when they supplied the answer the 1 was positive. Is that correct? This is how they wrote it y-0=2(x+1) I also cannot figure out how they got the slope. :(
 

skeeter

Senior Member
Joined
Dec 15, 2005
Messages
2,396
the point-slope form is ...

y - y<sub>1</sub> = m(x - x<sub>1</sub>)

the given point is (x<sub>1</sub> , y<sub>1</sub>) = (-1, 0)

substitute ...

y - 0 = m[x - (-1)] = m(x + 1)

see where the x+1 came from?

as far as the slope goes ... either it is given or there is another given point on the line so that it may be calculated.
 
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