# Question about common math operations.

• zeromodz
In summary, the conversation discusses the relationship between electric force and charge in the context of magnetism. It explains how the equation for electric field (E) can be derived from the equation for electric force (F) and the charge (q) involved. It also clarifies why it is necessary to cancel the q's instead of squaring them when simplifying the equation. The conversation ends with a mention of the different answers that can result from using different methods of simplification.

#### zeromodz

Okay say we know from magnetism.

E = F / q
F = KQq / R^2

Then we can say that.

E = KQq / (R^2 / q)

Then wouldn't we say
E = KQq * q / R^2
E = KQq^2 / R^2

Its just like saying.
5 / (1 / 2) = 5 * 2 / 1 = 10.

Why is it we cancel the q's instead of squaring them, because my textbook does that and ends up with this equation.
E = KQ / R^2

Because the answers are different. Thanks.

Last edited:
zeromodz said:
Okay say we know from magnetism.

E = F / q
F = KQq / R^2

Then we can say that.

E = KQq / (R^2 / q)
No, we can't say this.
It's really E = (KQq/R^2) / q, which is the same as (KQq/R^2) * (1/q). The order in which you do the division is significant.

It might be easier to see formatted as it usually is in print.
$$E = \frac{F}{q} = \frac{1}{q} F$$
$$= \frac{1}{q} \frac{KQq}{R^2}$$
$$= \frac{KQ}{R^2}$$

The q factors cancel because you have one of them in a numerator and the other in a denominator.
zeromodz said:
Then wouldn't we say
E = KQq * q / R^2
E = KQq^2 / R^2

Its just like saying.
5 / (1 / 2) = 5 * 2 / 1 = 20.
This is not right, either. 5/(1/2) = 5*2 = 10
zeromodz said:
Why is it we cancel the q's instead of squaring them, because my textbook does that and ends up with this equation.
E = KQ / R^2

Because the answers are different. Thanks.

## 1. What are the four basic math operations?

The four basic math operations are addition, subtraction, multiplication, and division.

## 2. Can you explain the order of operations in math?

The order of operations, also known as PEMDAS, stands for Parentheses, Exponents, Multiplication and Division (from left to right), and Addition and Subtraction (from left to right). This is the order in which mathematical operations should be performed in an equation to ensure the correct answer.

## 3. How do I solve a math problem with multiple operations?

To solve a math problem with multiple operations, you should follow the order of operations and complete the operations in parentheses first, then any exponents, followed by any multiplication or division from left to right, and finally any addition or subtraction from left to right.

## 4. What is the difference between multiplication and division?

Multiplication is the process of adding a number to itself a certain number of times, while division is the process of splitting a number into equal parts or groups.

## 5. How can I remember the order of operations in math?

A common mnemonic device for remembering the order of operations is "Please Excuse My Dear Aunt Sally," with the first letter of each word representing the order of operations (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction). You can also use the acronym PEMDAS.