SOLUTION: (-1,4)and (5,-8)

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Question 499813: (-1,4)and (5,-8)
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=-1 and y%5B1%5D=4.
Also, is the second point . So this means that x%5B2%5D=5 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=%28-8-4%29%2F%285--1%29 Plug in y%5B2%5D=-8, y%5B1%5D=4, x%5B2%5D=5, and x%5B1%5D=-1


m=%28-12%29%2F%285--1%29 Subtract 4 from -8 to get -12


m=%28-12%29%2F%286%29 Subtract -1 from 5 to get 6


m=-2 Reduce


So the slope of the line that goes through the points and is m=-2


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


y-4=-2%28x%2B1%29 Rewrite x--1 as x%2B1


y-4=-2x%2B-2%281%29 Distribute


y-4=-2x-2 Multiply


y=-2x-2%2B4 Add 4 to both sides.


y=-2x%2B2 Combine like terms.


So the equation that goes through the points and is y=-2x%2B2


Notice how the graph of y=-2x%2B2 goes through the points and . So this visually verifies our answer.
Graph of y=-2x%2B2 through the points and

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

Thanks,

Jim