what is the equation of the function

Question

write the slope intercept equation of the function f whose graph satisfies the given conditions.

 

the graph of f passes through (-3, -9) and is perpendicular to the line whose equation is x=3

 

the equation of the function is ?

Answer 1

Hi Vanity

 

First of all remember the slope intercept equation is y = mx + b or if they want it as a function you would say

f(x) = mx + b where m is the slope and b is the y intercept.

 

Now we know this line must pass thru a point on the line x = 3 which is a vertical line that passes the x axis at (3,0).  You know this line also passes thru the point (3, -9) and I am sure you can visualize that the line we would be looking for is the horizontal line that crosses our vertical line at this very point.  This horizontal line then crosses the y axis at (0, -9).  

 

You now have your b = -9 which is where the line intercepts the y axis.  You also know that a horizontal line has zero slope so your function is f(x) = 0x - 9, or f(x) = -9.

 

Hope this helps, try drawing it on graph paper.

 

All the best

 

Lori