if i'm asked to find f(5) and i have f(2) and f(3), can i change f(5) -> f(2+3) -> f(2) + f(3) ?

[Pliniao]

if i'm asked to find f(5) and i have f(2) and f(3), can i change f(5) -> f(2+3) -> f(2) + f(3) ?

 

[stapel]

if i'm asked to find f(5) and i have f(2) and f(3), can i change f(5) -> f(2+3) -> f(2) + f(3) ?

Only in *very* specific circumstances. In general, the answer is "no".

(If they'd given you any information about the function, then it might have been possible to give a specific answer.)

 

[Dr.Peterson]

if i'm asked to find f(5) and i have f(2) and f(3), can i change f(5) -> f(2+3) -> f(2) + f(3) ?

Please show the actual problem you are working on. Do you know anything at all about the nature of f?

If you are asking about a general method, the answer is that you can't find f(5) given only f(2) and f(3). You can see this by picking any function (except an exponential) and trying it.

 

[Steven G]

I see some trouble with your conjecture. f(5) = f(0+5) = f(0) + f(5), ie f(5) = f(0) + f(5). Now subtract f(5) from both sides and you arrive at 0 = f(0).
Surely you know that f(0) = 0 is NOT true for every function. ex: if f(x) = 7, then f(0) = 7 and if g(x) = x+6, then g(0)=6.
If f(x) = x², then f(3+5) = f(8) = 8²=64 while f(3)+f(5) = 9 + 25 = 34. Does 64=34??

 

[Steven G]

What you are describing is what is called a linear function, not to be confused with a linear function.

 

[Bruce]

a linear function, not to be confused with a linear function.

Is that a typo?

 

[Steven G]

Is that a typo?

I don't think so. Why do you think my stating is wrong.

 

[stapel]

Why do you think my stating is wrong.

"You are describing something that is an [x], which should not be confused with an [x]."

 

[Dr.Peterson]

"You are describing something that is an [x], which should not be confused with an [x]."

Ah, but words can have different meanings in different contexts:

Linear function - Wikipedia

en.wikipedia.org

Linear function - Wikipedia

en.wikipedia.org

Those are the two things that shouldn't be confused!

[x] is not always [x].

 

[Steven G]

Is that a typo?

Oops, you are correct, that is a typo.
I meant to say this is a linear function which is not to be confused with a linear function.

 

[Harry_the_cat]

What you are describing is what is called a linear function, not to be confused with a linear function.

 

[khansaheb]

I meant to say this is a linear function which is not to be confused with a linear function.

Did you mean to say linear form here?

You should really get a new pair of glasses !!!!!

 

[Steven G]

I need glasses and a new brain.
I meant to write (and will triple check) that this type of function is a linear function, not to be confused with a linear equation.

 

[Dr.Peterson]

I need glasses and a new brain.
I meant to write (and will triple check) that this type of function is a linear function, not to be confused with a linear equation.

And I was sure you had made a serious comment, that the sense in which you used "linear function" is the advanced sense, not the basic algebra sense. That's why I provided two different links, to show that it really did make sense.

 

[fersadilala2]

I need glasses and a new brain.
I meant to write (and will triple check) that this type of function is a linear function, not to be confused with a linear equation.