If f : R → R is defined by f(x)

Question:

If $f: R \rightarrow R$ is defined by $f(x)=x^{2}$, write $f^{-1}(25)$

Solution:

Let $f^{-1}(25)=x \quad \ldots(1)$

$\Rightarrow f(x)=25$

$\Rightarrow x^{2}=25$

$\Rightarrow x^{2}-25=0$

$\Rightarrow(x-5)(x+5)=0$

$\Rightarrow x=\pm 5$

$\Rightarrow f^{-1}(25)=\{-5,5\}$      $[$ from (1)]

Leave a comment

Close
faculty

Click here to get exam-ready with eSaral

For making your preparation journey smoother of JEE, NEET and Class 8 to 10, grab our app now.

Download Now