# Re-write equation without multiplication

• Oct 31st 2012, 01:20 PM
sfspitfire23
Re-write equation without multiplication
Hi guys,

I have an equation y = a*b + c*d

The variables are just real numbers. How can I get this equality to hold without multiplying anything together? I have tried taking the log of each side but that doesn't work.

Anyone have any thoughts?
• Oct 31st 2012, 05:25 PM
Soroban
Re: Re-write equation without multiplication
Hllo, sfspitfire23!

Are you sure of the wording of the problem?
I don't think it can be done.

Quote:

Rewrite without multiplication: . $y \:= \:ab + cd$
The variables are real numbers.

It might help if we knew what course this problem came from.

If the variables were natural numbers, the task can be completed.

. . $\text{For example: }\:a\cdot b \;=\;\underbrace{b + b + b + \cdots + b}_{a\text{ terms}}$

But with real numbers . . . I see no way to rewrite $\pi\sqrt{3}$
• Nov 1st 2012, 06:07 AM
sfspitfire23
Re: Re-write equation without multiplication
Just a linear algebra course. My teacher wants to know whether it can be done. I don't think it can.