# Combining equations help

1. May 27, 2012

### iqbal7

I am reading this in a book and am having trouble understanding this.

Can someone explain the step by step the process in changing equation A into equation B?

Mrc= 2/3Pcb x b x 1/2d1 x 3/4d1

= 1/4Pcb x b x (d1)2

Many Thanks

2. May 27, 2012

### DonAntonio

It is almost impossible to understand what you wrote (for me it is completely impossible). Please do learn how to use LaTeX within this site to write mathematics.

DonAntonio

3. May 27, 2012

### Stephen Tashi

4. May 27, 2012

### algebrat

Remember that multiplication, does not require any distribution, that is, some students write

A(BC)=(AB)(AC). This is wrong. They are thinking of A(B+C)=AB+AC.

So multiplication only needs to happen once.

you have a copy of 2/3, 1/2 and 3/4. Take the first two 2/3 and 1/2, their product is 1/3.

Then 1/3 times 3/4 is 1/4. They also have two copies of d1, so that is (d1)^2.

I'm assumig by d1, you meant d$_1$

5. May 29, 2012

### iqbal7

Thanks Algebrat,

You have explained it very clearly, and now I understand.