Q6  Let

  f = \left \{ \left ( x , \frac{x^2}{1+ x^2} \right ) : x \epsilon R \right \} 
R be a function from R into R. Determine the range
of f.

Answers (1)

Given function is 
f = \left \{ \left ( x , \frac{x^2}{1+ x^2} \right ) : x \epsilon R \right \}
Range of any function is the set of values obtained after the mapping is done in the domain of the function. So every value of the codomain that is being mapped is Range of the function.
Let's take
 y = \frac{x^2}{1+x^2}
\Rightarrow y(1+x^2)=x^2
\Rightarrow y+yx^2=x^2
\Rightarrow y=x^2(1-y)
\Rightarrow x^2= \frac{y}{1-y}
\Rightarrow x= \pm \sqrt{\frac{y}{1-y}}
Now, 1 - y should be greater than zero and y should be greater than and equal to zero for x to exist because other than those values the x will be imaginary
Thus, 1 - y > 0 , y < 1 \ and \ y \geq 0
Range of given function is  [0,1)