Let $f: R→R$ be defined by $f(x)=x^2,$ for every $x \in R$. Then f is :

one-one and onto one-one and not onto neither one-one nor onto onto and not one-one

neither one-one nor onto

The correct answer is Option (3) → neither one-one nor onto $f(x)=x^2$ $y=x^2⇒x=\sqrt{y}$ for $x<0$ y don't exist ⇒ Not onto for $f(1)=1^2=1=(-1)^2=f(-1)$ but $1≠-1$ ⇒ Not One one