what is the domain of the function?

Question

anonymous · Answer

$$y=\sqrt{4x-4}$$

jdoe0001 · Answer

well, what values can "x" take, bearing in mind that a negative number inside the root, will give you an imaginary answer

anonymous · Answer

$$y= 2\sqrt{x-1}$$

anonymous · Answer

thats what i got

anonymous · Answer

but its not one of my choices

jdoe0001 · Answer

so, what values will make "X" give a negative value inside the root?

anonymous · Answer

0?

anonymous · Answer

y=-2.5

jdoe0001 · Answer

so, what values will make "X" give a negative value inside the root?

anonymous · Answer

i dont know

jdoe0001 · Answer

ok, you have $$2\sqrt{x-1}$$
try giving a few values to "x", say -3,-2,-1,0,1,2,3

anonymous · Answer

its either




$$x >-1$$
$$x \ge1$$
$$x \ge-1$$
$$x \ge1$$

jdoe0001 · Answer

ok so, check with the values I've shown :)

jdoe0001 · Answer

what will "Y" or f(x) give you with those 7 values for "X"

jdoe0001 · Answer

or even other values to check with :), -1,000,000 and 1,000,000

anonymous · Answer

You can't do this by guessing values.  Three steps.

1.  Assume every number works.
2.  Find what doesn't work and discard.
3.  What's left is the domain.

In this case, the argument of the square root has to be at least zero, so$$4x-4 \ge 0 \implies x \ge 1$$

anonymous · Answer

In interval notation,$$x \in [1, \infty)$$

anonymous · Answer

okay thanks :)