Why do they use letters in algebra?

Question

I do not understand algebra. Can someone give an example of an algebra formula used at a job, where they can show my why letters are used? I am not a formula guy. I need working job examples. Thanks.

Answer 1

well the letter is a variable and the number is unknown, but is an example where you do know the value of the variable:

x= multiply btw and / means divide

y x w+ 4/2      if y=21 and w= 12

here is how to solve it:

y x w+ 4/2

21x12+ 4/2

21x12= 252

252+4/2

4/2= 2

252+2= 254

so you final answer is 254, this was a simple and easy example hopefully you kinda understand more now, I hope I helped! Good Luck! I know this can be tough be practice does make perfect! lol :)

Answer 2

the letter represent whats called a variable or an unknown.

so if you see something like

x + 3 = 5

you could read that as what number (or x) plus 3 =5

so in this case x = 2

common letters used in alegebra are x, y, n, m, z...

Answer 3

The letters represent variables, things that may change and/or values we do not know.

Example:

Bob finishes a job in 10 minutes.

Bill finishes in 13 minutes.

Smith finishes in 6 minutes.

How long will it take for them to finish the job together?

Bob finished 1/10 of the job in 1 minute.

Bill finishes 1/13.

Smith finishes 1/6.

Together they finish:

(1/10)+(1/13)+(1/6) of the job in one minute.

That's:

67/195 of the job in one minute

So, in 195/67 minutes, the job is complete.

Thats 2 61/67, approximately 3 minutes.

However, lets look at the same problem again, without knowing any numbers.

Bob can finish in x minutes.

Bill in y minutes.

Smith in z minutes.

So, they finish:

(1/x), (1/y), and (1/z)

of the job in one minute respectively.

So, together, they finish:

(1/x)+(1/y)+(1/z)

taking the LCD as xyz, we get:

(xy+xz+yz)/(xyz)=1/t

For time t.

This means the reciprocal of both sides must also be equal, so we get:

xyz/(xy+xz+yz)=t

So, now we are told:

x=10, y=6, z=13

So, all we do is plug in to get:

xyz=780

xy=60

xz=130

yz=78

xy+xz+yz=268

t=780/268=2 61/67 or approx. 3

So, if you had 100 questions like this, you would not want to go and show ur work for each one. Instead, you would prefer to just plug in each time.

Variables are an enormous part of math, not just algebra.

Peace

Answer 4

>>Why do they use letters in algebra?

They're called variables, and they're used to represent numbers.  Sometimes you don't know what number you're looking for, but you do know the results of what happens to those numbers.  Using variables lets you set up equations and work backwards to arrive at the answer you need.

Consider this problem: you own a coffee shop and you have one grade of beans that costs $4.50 per pound, and another grade that costs $5.35 per pound.  You want a 10 pound mixture that you can sell for $5.00 per pound.  How much of each do you put in?  You'd go mad if you tried to solve this simple problem without algebra.

Read this:

http://mathforum.org/library/drmath/view...

http://mathforum.org/library/drmath/view...

You say you're "not a formula guy", yet you want me to give you an example of a formula.  So which is it?

Answer 5

To make the question more understandable.

e.g 5x+6=3 u know if they say 5+6=3 it's meaningless but adding an unknown makes it sensible.

so 5x+6=3  = 5x=3-6  5x=-3   divide both sides by the one with x i.e 5

so x=-3/5