SOLUTION: How do I Figure this out? Write an equation, in slope-intercept form , Given f(-5)=-45, and f(0)=-5

Algebra ->  Graphs -> SOLUTION: How do I Figure this out? Write an equation, in slope-intercept form , Given f(-5)=-45, and f(0)=-5      Log On


   

Question 362570: How do I Figure this out?
Write an equation, in slope-intercept form , Given f(-5)=-45, and f(0)=-5
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
f(-5)=-45, and f(0)=-5 means that we have the points (-5,-45) and (0,-5). The line then goes through these points.


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


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


m=%28-5--45%29%2F%280--5%29 Plug in y%5B2%5D=-5, y%5B1%5D=-45, x%5B2%5D=0, and x%5B1%5D=-5


m=%2840%29%2F%280--5%29 Subtract -45 from -5 to get 40


m=%2840%29%2F%285%29 Subtract -5 from 0 to get 5


m=8 Reduce


So the slope of the line that goes through the points and is m=8


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--45=8%28x--5%29 Plug in m=8, x%5B1%5D=-5, and y%5B1%5D=-45


y--45=8%28x%2B5%29 Rewrite x--5 as x%2B5


y%2B45=8%28x%2B5%29 Rewrite y--45 as y%2B45


y%2B45=8x%2B8%285%29 Distribute


y%2B45=8x%2B40 Multiply


y=8x%2B40-45 Subtract 45 from both sides.


y=8x-5 Combine like terms.


So the equation that goes through the points and is y=8x-5