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# Help Please Its Really Important!! watch

find the domain:

f(x) = √(3-x)/ modulus x + x

and

f(x) = modulus(x-1) - modulus (x+1)

(plus range for this one!)

plz help guys!! plz
2. (Original post by ossoss87)

find the domain:

f(x) = √(3-x)/ modulus x + x

and

f(x) = modulus(x-1) - modulus (x+1)

(plus range for this one!)

plz help guys!! plz
Well, for the first one, you have as the domain. This is because for any such that you have an imaginary numerator. For any number such that , you are dividing by 0, which gives an undefined answer. Use this type of thinking for the second one.
4. (Original post by ossoss87)
No problem. Let's take a few examples.

If , we have:

That is

Since we're defining the domain over real numbers only, we can't take any values for . Hence, or (whichever takes your fancy ).

Now, for values of x such that x is negative (i.e. ), we have (taking -1 as an example):

This is undefined. This is the case for all negative numbers, and 0. Thus, we take . So, our domain is the union of these two inequalities. (i.e. ). Hope that helps.

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Updated: November 11, 2005
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