# Homework Help: Simple but cant solve it

1. May 20, 2010

### greg997

Can someone show me in steps how to manipulate this formula in attachement to obtain 1/(sqr(w^2+4)? Thanks

#### Attached Files:

• ###### Untitled.jpg
File size:
6.1 KB
Views:
184
2. May 20, 2010

### jack action

The two equations are not equal. Just replace w by any value and you'll see that both equations give different answers.

3. May 20, 2010

### Mentallic

The best you can really get is:

$$\frac{\sqrt{4-w^2}}{w^2+4}$$

Last edited: May 20, 2010
4. May 20, 2010

### Mentallic

You must have made a typo. The expression should be,

$$\sqrt{\left(\frac{2}{w^2+4}\right)^2+\left(\frac{w}{w^2+4}\right)^2}$$

5. May 20, 2010

### greg997

Hmm, thats quite possible. Then how to get that solution?

6. May 20, 2010

### Mentallic

Well I can't just give you the answer, you need to show an attempt at solving the problem first.

But I can give you some hints, you can most certainly find the answer by using a combination of these rules:

$$\sqrt{\frac{a}{b}}=\frac{\sqrt{a}}{\sqrt{b}}$$

$$\sqrt{a^2b}=|a|\sqrt{b}$$ (the |a| means the positive of a, but remember that for any real number n, n2 is always positive).

$$\frac{a}{c}+\frac{b}{c}=\frac{a+b}{c}$$

$$\frac{\sqrt{a}}{a}=\frac{1}{\sqrt{a}}$$

Good luck!

7. May 21, 2010

### greg997

Hello, I am sorry but it just does not work. What am I doing work? Thanks

#### Attached Files:

• ###### 1.jpg
File size:
11.2 KB
Views:
114
8. May 21, 2010

### Cyosis

You're adding fractions, but you're multiplying numerators.

9. May 21, 2010

### greg997

AAA, stupid me:) Thanks