# P = V * ( V / R ) = V2 / R

#### Jerramundi

##### Senior Member
Because you would be inserting an extra 1/R in the equation that wasn't there in the first place.
@Carultch is correct. To put it simply, you're inserting an extra R in your V*V/R*R

When we first learned about the Distributive Property way back when, we used to draw arrows to help it make sense, like this:

The B and C here are two different values, both "receive" the A.

I think the reason you're getting confused is because the ( V / R ) is spaced out horizontally, because you have to do it that way when typing, and it looks similar to the B + C.

You have to think of the ( V / R ) as ONE number, A FRACTION. So when you distribute the V it actually looks like this:

When you multiple by a fraction ( V / R ), you have to convert the whole number ( V ) to a fraction too... because those are simply the rules of multiplying fractions. You multiply the top two numbers (i.e. numerators) and the bottom two numbers (i.e. denominators) separately.

Any number divided by 1 is equal to itself.

#### Jerramundi

##### Senior Member
You mean he got a defective brain?
Wizard probably sold him a brain made in Chiner.

#### myspark

##### Senior Member
Here's a basic list off mathematical properties/laws:
• Commutative Property of Multiplication
• Associative Property of Multiplication
• Multiplicative Identity Property
• Multiplicative Inverse Property
• Multiplicative Property of Zero
• Substitution Property
• Distributive Property
• Division Property
• Inverse Property of Inequality/Equality
There are more, but it's a good starting point.

Those GUIDELINES are sort of STARE DECISIS (pronounced stah-ree). In Latin means “it’s been done, so that’s the way it shall be.”.
What this implies is ROTE LEARNING.

Basic properties are necessary in early learning of Math.
It is taught in early stages.. . . but in advanced HOTS (Higher Order Thinking Skills) this ROTE LEARNING is simply memorization based on repetition.

This type of learning deprive student the ability to analyze, comprehending, application and evaluation. In other words CRITICAL THINKING is missing.
This is an approach before an exam is conducted often called “CRAMMING”. I know I did it it myself when I was a student. Chances of passing the test is likely. . . but can be forgotten easily.

As a student go into HOTS like higher MATHs. . . as in Algebra, Trigonometry , Differential and Integral Calculus--rote learning becomes a hindrance because lessons are far more engaged in decision-making.

Cumulative Algebra is carried all through the pursuit of higher Math especially this CUMULATIVE CALCULUS--along with other Engineering Fundamentals (FE).

#### Hv&Lv

##### Senior Member
Had a PE tell me one time years ago it’s not what you learned, it what you understood

#### Jerramundi

##### Senior Member
Those GUIDELINES are sort of STARE DECISIS (pronounced stah-ree). In Latin means “it’s been done, so that’s the way it shall be.”.
What this implies is ROTE LEARNING.
I posted those "guidelines" because it was clear to me that the OP was lacking in an understanding of these "guidelines" and you gotta start somewhere. Why not start with a basic Wikipedia list of Mathematical Principles and go from there? The validity of Wikipedia as a source is often challenged, and sometimes rightfully so, but it still often provides a good "jumping off point."

I don't see what specifying what "type of learning" these fall under accomplishes other than to start a debate about our country's education system, which may be merited in other contexts, but really does nothing to help the OP move forward.

#### myspark

##### Senior Member
Had a PE tell me one time years ago it’s not what you learned, it what you understood
Exactly.
As Einstein once said:
If everything is understood during the learning process, it becomes really hard to forget.

Education is what remains after everything else is forgotten.

Albert Einstein

#### kreemoweet

##### Member
The "alt" key codes on Windows are not Unicode, it's just some stuff Microsoft thought up one day. The real Unicode
for "superscript 2" is "00B2". On a Linux system, you can enter unicode characters by typing <CTRL>+<SHIFT>+<u>, and
then the 4 digits of the unicode codepoint. Like this: ²

#### synchro

##### Senior Member
The "alt" key codes on Windows are not Unicode, it's just some stuff Microsoft thought up one day. The real Unicode
for "superscript 2" is "00B2". On a Linux system, you can enter unicode characters by typing <CTRL>+<SHIFT>+<u>, and
then the 4 digits of the unicode codepoint. Like this: ²
Or on a Mac you enter the hexadecimal digits for Unicode characters with the Option key, provided that you've selected "Unicode Hex Input" in the keyboard preferences.

#### romex jockey

##### Senior Member
ok, who let the EE's off their leash again?.... ~RJ~

#### WasGSOHM

##### Senior Member
Here’s one.

Conductance (C) is proportional length (L) and wire temperature (T).
Bear in mind that more L = less C and more T = less C.
Which formula is most nearly correct?

C = 1/(LxT)
C = 1/L/T
neither

By the way, how do I quote posts? It used to work for me.

V2

#### WasGSOHM

##### Senior Member
Here’s another.

Convert 6 ohms per kilometer into ohms per meter.
(6 ohms/km) x (km/1000 meters).
The km cancel out and so you are left with ohms per meter. It’s 0.006 ohm or 6E-3 ohm.

If you did
(6 ohms/km)x(1000 m/km)
it’s wrong, the kms did not cancel out and you get (6000 ohms x m) per (km^2).

If you're up to it, convert 100 yards in 10 seconds to mm per microsecond.

#### Carultch

##### Senior Member
If you're up to it, convert 100 yards in 10 seconds to mm per microsecond.

Write down what we are given:
(1000 yd) / (10 sec)

Multiply by 1 in a fancy way, for each unit you desire to cancel
1 = 36 in / yd
1 = 25.4 mm/in
1 = 1e6 mu-sec/sec
1 = 1e-6 sec/mu-sec

(1000 yd / 10 sec) * (36 in/yd) * (25.4 mm/in) * (1e-6 sec/mu-sec) =
0.09144 mm/mu-sec

#### kwired

##### Electron manager
Here’s another.

Convert 6 ohms per kilometer into ohms per meter.
(6 ohms/km) x (km/1000 meters).
The km cancel out and so you are left with ohms per meter. It’s 0.006 ohm or 6E-3 ohm.

If you did
(6 ohms/km)x(1000 m/km)
it’s wrong, the kms did not cancel out and you get (6000 ohms x m) per (km^2).

If you're up to it, convert 100 yards in 10 seconds to mm per microsecond.

Easy, ask how to do it on here and whatever answer comes up the most is likely correct

#### WasGSOHM

##### Senior Member
Write down what we are given:
(1000 yd) / (10 sec)

Multiply by 1 in a fancy way, for each unit you desire to cancel
1 = 36 in / yd
1 = 25.4 mm/in
1 = 1e6 mu-sec/sec
1 = 1e-6 sec/mu-sec

(1000 yd / 10 sec) * (36 in/yd) * (25.4 mm/in) * (1e-6 sec/mu-sec) =
0.09144 mm/mu-sec
I got 9.144E-3. These things still make me nuts.

#### Besoeker3

##### Senior Member
I got 9.144E-3. These things still make me nuts.
Simple. Use SI...........

#### Hv&Lv

##### Senior Member
Simple. Use SI...........
Oh! now you’ve shook that hornets nest...