Answer with explanation:
If an expression, f(x)=y, is a function, then for every y , there is unique x and for every x, there is unique y.
⇒f(3)=1, means ,when in the expression, x is substituted by, 3 , the value of y is 1.
⇒x(Domain) y(Range)
3 1
The Set of values that x can take is called Domain of the function, and the set of values that y can take is called Range of the function.