# Multiplying Variables

1. May 6, 2009

### Stratosphere

1. The problem statement, all variables and given/known data
How would I multiply this together? (3$$\sqrt{2x}$$)(3$$\sqrt{2x}$$)

2. Relevant equations

3. The attempt at a solution
I can't seem to be able to figure out how to multiply them, i keep getting an answer that is too short.

Last edited: May 6, 2009
2. May 6, 2009

### Dick

What do you get?? And are those supposed to be cube roots or 3 times a square root?

3. May 6, 2009

### Stratosphere

3 times a square root. Sorry if it’s not clear.

4. May 6, 2009

### Dick

That's fine. So what did you get?

5. May 6, 2009

### HallsofIvy

Staff Emeritus
Well you should be able to say what $\sqrt{2x}\sqrt{2x}$ is just from the definition of square root! And I'm sure you know what (3)(3) is!

But are you absolutely sure it is $(3\sqrt{2x})(3\sqrt{2x})$? That's seems a peculiar way to write a very simple question. $(\sqrt[3]{2x})(\sqrt[3]{2x})$ is a much more reasonable (and slightly harder) question.

6. May 6, 2009

### Stratosphere

Let me rephrase the question. I want to know how to multiply somthing like
(2-$$\sqrt{x-1}$$)(2-$$\sqrt{x-1}$$), in other words, how to square a side that has variables in a radical.
After i did this out i got
-4$$\sqrt{x-1}$$+x+3

7. May 6, 2009

### Dick

And what could be wrong with that?

8. May 7, 2009

### symbolipoint

Commutative and associative properties will let you group the like factors together. You see each factor is squared. 3$$\bullet$$3$$\bullet$$$$\sqrt{2x}$$$$\sqrt{2x}$$, and then just one or two more steps if any.

EDIT: While trying to edit this, to fix the LARGE dots representing multiplication, the typesetting formatting tool is gone; those should really be small dots as can be common for showing multiplication operation. I do not have many of these tags memorized for TEX.

Last edited: May 7, 2009
9. May 7, 2009

### symbolipoint

Let me continue:

(3)(3)$$\sqrt{2}$$$$\sqrt{2}$$$$\sqrt{x}$$$$\sqrt{x}$$

edit: this time, the forum will NOT permit me to put in the missing square root of x. It is present in the message edit field, but will not appear in the resulting forum message.

Last edited: May 7, 2009