What is the domain and range of y=12x2+4?

1 Answer
Oct 21, 2014

Consider the function y=f(x)

The domain of this function is all the values of x for which the function holds. The range is all those values of y for which the function is valid.

Now, coming to your question.
y=x22+4
This function is valid for any real value of x. Thus the domain of this function is the set of all real numbers, i.e. , R.

Now, separate out x.
y=x22+4

=> y4=x22

=> 2(y4)=x2

=> {2(y4)}12=x

Thus, the function is valid for all real numbers greater than or equal to 4. Therefore the range of this function is [4, ).