MCQ
If $f(x)=x+1$, find $\frac{d}{d x}(f o f)(x)$.
  • A
    0
  • 1
  • C
    $x$
  • D
    $3 x^2$

Answer

Correct option: B.
1
(b) : Given, $f(x)=x+1$
Now, $(f o f)(x)=f(f(x))=f(x+1)=(x+1)+1=x+2$
$\therefore \quad \frac{d}{d x}(f o f)(x)=\frac{d}{d x}(x+2)=1$

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