


Functions
Started by davidmarsh01, Sep 10 2009 03:21 PM
7 replies to this topic
#1
Posted 10 September 2009 - 03:21 PM
Hello, this is my first post so go easy on me
. Could anyone help me with this functions question? The function f(x)=a/x +b is such that f(-1)=3/2 and f(2)=9. Find the values of a and b. Thanks for any help

#2
Posted 10 September 2009 - 03:29 PM
good al fashioned simultaneous equations
first substitute in the two points given to get two equations
-1=a/(3/2) + b
-1=2a/3 + b
and
2=a/9+b
and solve using simultaneous equations
answers should be , I think XD
a=-5.4, b =2.6
any other questions just post again
first substitute in the two points given to get two equations
-1=a/(3/2) + b
-1=2a/3 + b
and
2=a/9+b
and solve using simultaneous equations
answers should be , I think XD
a=-5.4, b =2.6
any other questions just post again

=-=-=Marcus=-=-=
#3
Posted 10 September 2009 - 03:33 PM
QUOTE (Marcus @ Sep 10 2009, 04:29 PM) <{POST_SNAPBACK}>
good al fashioned simultaneous equations
first substitute in the two points given to get two equations
-1=a/(3/2) + b
-1=2a/3 + b
and
2=a/9+b
and solve using simultaneous equations
answers should be , I think XD
a=-5.4, b =2.6
any other questions just post again
first substitute in the two points given to get two equations
-1=a/(3/2) + b
-1=2a/3 + b
and
2=a/9+b
and solve using simultaneous equations
answers should be , I think XD
a=-5.4, b =2.6
any other questions just post again

I thought that if f(-1) = 3/2 then -1 would have to go in for the x term and 3/2 would go in for the f(x)? You seemed to do it the other way round?
#4
Posted 10 September 2009 - 04:02 PM
lol yeah you're right XD....I was em....testing you that's it
sorry XD

sorry XD
=-=-=Marcus=-=-=
#5
Posted 10 September 2009 - 04:05 PM
QUOTE (Marcus @ Sep 10 2009, 04:29 PM) <{POST_SNAPBACK}>
good al fashioned simultaneous equations
first substitute in the two points given to get two equations
-1=a/(3/2) + b
-1=2a/3 + b
and
2=a/9+b
and solve using simultaneous equations
answers should be , I think XD
a=-5.4, b =2.6
any other questions just post again
first substitute in the two points given to get two equations
-1=a/(3/2) + b
-1=2a/3 + b
and
2=a/9+b
and solve using simultaneous equations
answers should be , I think XD
a=-5.4, b =2.6
any other questions just post again

and f(x)=3/2 it is the whole function that is equal to 3/2 not just the x as you subbed in
#6
Posted 10 September 2009 - 04:09 PM
QUOTE (Marcus @ Sep 10 2009, 05:02 PM) <{POST_SNAPBACK}>
lol yeah you're right XD....I was em....testing you that's it
sorry XD

sorry XD
so what is the answer?
#7
Posted 10 September 2009 - 04:18 PM
QUOTE (davidmarsh01 @ Sep 10 2009, 05:09 PM) <{POST_SNAPBACK}>
QUOTE (Marcus @ Sep 10 2009, 05:02 PM) <{POST_SNAPBACK}>
lol yeah you're right XD....I was em....testing you that's it
sorry XD

sorry XD
so what is the answer?
i have it! b=6.5 and a=5

#8
Posted 10 September 2009 - 09:25 PM
i was having problems with this myself, this topic baffles me
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