# Finding inverse?

1. Jul 4, 2007

Q.1: How can we find the inverse of a fraction?
e.g . 1/2-(sqrt)3 .

Q.2: A' intersection (A union U).

2. Jul 4, 2007

### cristo

Staff Emeritus
What do you mean by the inverse of a fraction? Do you mean the reciprocal? If so, turn this into an improper fraction and take the reciprocal of that.

What do you think? What are A, A' and U?

3. Jul 4, 2007

### symbolipoint

Q.1: What kind of inverse are you asking? Arithmetic inverse (additive or multiplicative, some other arithmetic kind); or function inverse (which requires a function, not a constant value only)?

Q.2: WHAT?

4. Jul 5, 2007

### HallsofIvy

Staff Emeritus
To add to the questions, does "1/2-(sqrt)3" mean $$\frac{1}{2}-\sqrt{3}$$ or $$\frac{1}{2-\sqrt{3}}$$.
If the former, and if by "inverse" you mean reciprocal, then $$\frac{1}{2}-\sqrt{3}= \frac{1-2\sqrt{3}}{2}$$ and its reciprocal is $$\frac{2}{1-2\sqrt{3}}$$. You can "pretty" that up by rationalizing the denominator.

For the second problem, I'm going to assume that "U" is the universal set and A' is the complement of A.

What is the union of U with any set? What is the intersection of U with any set?

5. Jul 5, 2007

really really sorry Halsof actualy it is
1/(2-sqrt3). I will be thankful to you if you find the inverse of this.

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Last edited: Jul 5, 2007
6. Jul 5, 2007

### cristo

Staff Emeritus
Firstly, you should note that we do not give out answers to homework/coursework type questions here. Secondly, you still haven't defined "inverse." Is it the reciprocal you want? If so, what is the reciprocal of a fraction of the form a/(b+c)?

7. Jul 5, 2007

### HallsofIvy

Staff Emeritus
I will echo- what do you mean by "inverse"? The multiplicative inverse (reciprocal)? If so the problem is pretty close to trivial.