# A lil algebra help

1. Sep 14, 2005

### DB

to solve for d_2:
$$\frac{336}{81}=\frac{175}{100}*\frac{1}{[\frac{d_2}{0.1}]^3}$$
$$\sim 2.4=\frac{1}{[\frac{d_2}{0.1}]^3}$$

then i dont know wat to do i know its simple algebra, i just dont see it,.

2. Sep 14, 2005

### Staff: Mentor

If $$a = \frac{1}{b^3}$$
Then $$b^3 = \frac{1}{a}$$

Use this idea and keep going.

3. Sep 14, 2005

### DB

thnx 4 all the help doc,
i get
$$d_2=0.041^{\frac{1}{3}}$$

4. Sep 14, 2005

### Staff: Mentor

That doesn't seem right. Consider the following:
$$[\frac{d_2}{0.1}]^3 = \frac{d_2^3}{0.001}$$

5. Sep 14, 2005

### DB

o i see wat i did, so $$d_2=[4.1*10^{-4}]^\frac{1}{3}$$?

6. Sep 14, 2005

### Staff: Mentor

Much better.

7. Sep 14, 2005

### Ouabache

Even better if you don't convert your constants to a decimal so soon.
Keep them as fractions and you should find you can easily take their cube root later.