MCQ
વિધેય $f:R \to R$ ; $f(x) = {e^x}$ એ . . .
- Aવ્યાપ્ત
- Bઅનેક એક
- ✓એક-એક છે અને વ્યાપ્ત નથી
- Dએક-એક નથી અને વ્યાપ્ત છે.
Let ${x_1},\,{x_2} \in R$ and $f({x_1}) = f({x_2})$ or ${e^{{x_1}}} = {e^{{x_2}}}$ or ${x_1} = {x_2}$.
Therefore $f$ is one-one. Let $f(x) = {e^x} = y$.
Taking $log$ on both sides, we get $x = \log y$.
We know that negative real numbers have no pre-image or the function is not onto and zero is not the image of any real number.
Therefore function $f$ is into.
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