# Letters in expressions and formulas

#### Grog85

Hello, first post for me so I am sorry if this is in the wrong topic.

I'm am from the UK studying A-Level Physics.

I understand some formulas but this is testing me. Before I message my tutor I thought I would try here. Looks like a very useful website.

Letters in expressions and formulas.

v2 = u2 + 2as

I normally understand maths when I know the rules.

2 × 5 is written as 2 × 5 or 10
2 × a is written as 2a
a × b is written as ab

I don't seem to understand this and I can't seem to find helpful information and I will not skip the page.

Sorry if this is in the wrong topic and thank you for your help.

#### DrClaude

Mentor
v2 = u2 + 2as
Do you mean $u^2$ and $v^2$, with the 2 small and high? In that case, it is called an exponent and, in the present case, means "squared":
$$u^2 = u \times u$$
and
$$v^5 = v \times v \times v \times v \times v$$
You can have a look at Wikipedia for what it means when the exponent is not a positive integer.

#### Mentallic

Homework Helper
Multiplication is used so much in maths that it's simply much easier to get rid of the $\times$ symbol. This also meant that the letter $x$ could be used as a variable (and it's used a lot) without running into problems of ambiguity between it being a variable or a multiplication symbol.

Whenever you have a situation like $2\times 5$ then you're expected to evaluate that to 10, while $2\times a=2a$ cannot be simplified further so it's ok to leave as it is.

Other than that, I don't see what's so confusing about the notation.

#### Grog85

Do you mean $u^2$ and $v^2$, with the 2 small and high? In that case, it is called an exponent and, in the present case, means "squared":
Yes, small 2 above the u.

Thank you for your help. I'll see how I get on.

#### SteamKing

Staff Emeritus
Homework Helper
You must have missed a couple of days in algebra class.

#### Mark44

Mentor
Grog85, if you're going to be studying physics, you'll need to get the algebra difficulties squared away first.

Homework Helper
Gold Member
2018 Award

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