# The ambiguous question came to my last week exam

1. Mar 28, 2012

### abrowaqas

1. The problem statement, all variables and given/known data

If f(x) = x^3,
show that
f(a,b,c) = a+b+c

2. Relevant equations

I have given exam last week. and i am still searching for this question .. what this is about. is it from Tensor coordinate transformation or some numerical analysis involve here.

3. The attempt at a solution

2. Mar 28, 2012

### Staff: Mentor

As stated here, the question doesn't make sense. Your function f takes a single argument, so you could evaluate f(a), or f(b), or f(c), but not f(a, b, c).

3. Mar 28, 2012

### abrowaqas

But this question came in final Exam ... It has no error as paper setter claimed ..

How it will be solved ?
Anybody kindly help to solve this question

4. Mar 29, 2012

### Office_Shredder

Staff Emeritus
If this is the full problem statement as given, it has no solution because it doesn't make any sense. What is the definition of f(a,b,c) supposed to be?

5. Mar 29, 2012

### tazzzdo

Here you go:

Given a function f:ℝ → ℝ

f(x) := x3

f(a, b, c) := a + b + c

where x, a, b, c $\in$ ℝ

QED by trivialization.

lol now it's formal

6. Mar 30, 2012

### abrowaqas

7. Mar 30, 2012

### HallsofIvy

Staff Emeritus
It's hard to be serious about non-sense. And it is still non-sense. However you define "f(x)" that gives you NO information about "f(a, b, c)". They can't be the same function.