Find the domain in y=sqrt(4-x)?

1 Answer
Mar 19, 2018

x<=4 or (-oo,4]

Explanation:

Since this is a square root, the values inside cannot be lesser that 0. Else, you would end up with an imaginary number. So, with that information, we can write the inequality:

4-x>=0

Solve for x:

=> -x>=0-4

=>-x>=-4

Now, when we multiply both sides by a negative, we have to switch the signs:

(-1)-x<=(-1)-4

x<=4

We can also represent this as:

(-oo,4]

And there we have our answer.