Answer:
The given statement can be disproved by giving a simple counter-example
Using proof by contradiction method:
Let
[tex]f(x)=x^{2}[/tex]
Let
[tex]x=2\\\\\therefore f(2)=2^{2}=4[/tex]
Let
[tex]y=-2\\\\\therefore f(-2)=(-2)^{2}=4[/tex]
As we can see that
[tex]f(x)=4\\\\f(y)=4\\\\\therefore f(x)=f(y)\\\\But\\x\neq y(\because 2\neq-2)[/tex]
This completes our proof by contradiction.
