Question

If f is an identity function, then the value of f(1)-2f(2)+f(3)

Answer 1

$\textbf{Concept:}$

Let A and B be two sets.

A function from A to B is defined by f(x)=x is

called an identity function.

$\textbf{Given:}$

$\text{f is an identity function}$

$\textbf{To find:}$

$\text{The value of \bf\,f(1)-2\,f(2)+f(3) }$

$\textbf{Solution:}$

$\text{Since f is an identity function, we have f(x)=x }$

$\implies$

$f(1)=1$

$f(2)=2$

$f(3)=3$

$\text{Now,}$

$f(1)-2\,f(2)+f(3)$

$=1-2(2)+3$

$=4-4$

$=0$

$\therefore\textbf{The value of \bf\,f(1)-2\,f(2)+f(3) is 0}$

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