SOLUTION: How do I find the slope between the points (-4,-1) and (-2,8) Then it asks me to write a point slope equation for the line

Algebra ->  Expressions-with-variables -> SOLUTION: How do I find the slope between the points (-4,-1) and (-2,8) Then it asks me to write a point slope equation for the line      Log On


   

Question 924328: How do I find the slope between the points (-4,-1) and (-2,8)
Then it asks me to write a point slope equation for the line
Found 2 solutions by josgarithmetic, jim_thompson5910:
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
The meaning of slope is vertical change divided by horizontal change. Using the formula for slope as described, evaluate m=%288-%28-1%29%29%2F%28-2-%28-4%29%29.

What is the point-slope form equation for a line?
This comes from the formula for slope.
Unknown point (x,y);
Known point (u,v) on the line;
Slope is m=%28y-v%29%2F%28x-u%29. Multiply both sides by the denominator of the right side,
%28x-u%29m=y-v
highlight_green%28y-v=m%28x-u%29%29, the point-slope form of a line.

You have two known, given points for the line that you want to find.

You should have little or no trouble continuing and finishing the question.

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

First let's find the slope of the line through the points and


Note: is the first point . So this means that x%5B1%5D=-4 and y%5B1%5D=-1.
Also, is the second point . So this means that x%5B2%5D=-2 and y%5B2%5D=8.


m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula.


m=%288--1%29%2F%28-2--4%29 Plug in y%5B2%5D=8, y%5B1%5D=-1, x%5B2%5D=-2, and x%5B1%5D=-4


m=%289%29%2F%28-2--4%29 Subtract -1 from 8 to get 9


m=%289%29%2F%282%29 Subtract -4 from -2 to get 2


So the slope of the line that goes through the points and is m=9%2F2


Now let's use the point slope formula:


y-y%5B1%5D=m%28x-x%5B1%5D%29 Start with the point slope formula


y--1=%289%2F2%29%28x--4%29 Plug in m=9%2F2, x%5B1%5D=-4, and y%5B1%5D=-1


y--1=%289%2F2%29%28x%2B4%29 Rewrite x--4 as x%2B4


y%2B1=%289%2F2%29%28x%2B4%29 Rewrite y--1 as y%2B1


and you're done. The equation is in point slope form and it is simplified.


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Let me know if that helps or not. Thanks.

If you need more help, feel free to email me at jim_thompson5910@hotmail.com

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