+0  
 
0
465
1
avatar+227 

Here's my problem for today:

If f(x) = {(2,3),(4,5),(7,2)} and g(x) = {(2,1),(3,2),(7,4)}, then determine (f+g)(2) and (f(g(7)).

 

I have no clue how to do this. Help please!

ThisGuy  Jun 26, 2015

Best Answer 

 #1
avatar+87301 
+10

(f + g)(2)  =  f(2)  + g(2)   .........notce that   f(2) means that we are just asking what "y" value is associated with x in the function "f" when x = 2  ......this is the point (2,3)......so  f(2)  = 3

 

Likewise, g(2)   = 1

 

So......  (f + g)(2) = f(2) + g(2)  =  3 +  1 =   4

 

 

--------------------------------------------------------------------------------------------------------------------------

f(g(7)).....this means that, first, we are putting "7" into "g"  an finding the y value associated with that x value.....this is the point (7,4)....so   g(7) = 4

 

So....so far  ......f(g(7))  =  f(4).....now.......we are putting "4" into "f" and finding the y value associated with that x value.......this is the point (4,5)......so f(4)  = 5

 

To recap......f(g(7)  = f(4)  = 5

 

These are known as "composite" functions.....I'll admit they ARE a little tough to grasp !!!!

 

Post some more questions if you get stuck.....!!!

 

 

  

CPhill  Jun 26, 2015
 #1
avatar+87301 
+10
Best Answer

(f + g)(2)  =  f(2)  + g(2)   .........notce that   f(2) means that we are just asking what "y" value is associated with x in the function "f" when x = 2  ......this is the point (2,3)......so  f(2)  = 3

 

Likewise, g(2)   = 1

 

So......  (f + g)(2) = f(2) + g(2)  =  3 +  1 =   4

 

 

--------------------------------------------------------------------------------------------------------------------------

f(g(7)).....this means that, first, we are putting "7" into "g"  an finding the y value associated with that x value.....this is the point (7,4)....so   g(7) = 4

 

So....so far  ......f(g(7))  =  f(4).....now.......we are putting "4" into "f" and finding the y value associated with that x value.......this is the point (4,5)......so f(4)  = 5

 

To recap......f(g(7)  = f(4)  = 5

 

These are known as "composite" functions.....I'll admit they ARE a little tough to grasp !!!!

 

Post some more questions if you get stuck.....!!!

 

 

  

CPhill  Jun 26, 2015

18 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.