Algebra Help

[markem]

Originally Posted by Darrell

Is this Algebra?

2x x 4 = 100

Where the x is 5 making it 25x4=100?

I'm not so good at Math, lol.

Yes. It is an equation in a single variable.

However, x is NOT 5. Here's the details

2x X 4 = 100

Divide both sides by 4 and we get

2x = 25

divide both sides by 2 and we get

x = 25/2 = 12.5

Originally Posted by markem

Yes. It is an equation in a single variable.

However, x is NOT 5. Here's the details

2x X 4 = 100

Divide both sides by 4 and we get

2x = 25

divide both sides by 2 and we get

x = 25/2 = 12.5

So, if the equation is 2x X 4 = 100, will I always take the 100 and divide it by the number that was originally multiplied to get 100? In this case 4.

[markem]

Originally Posted by Darrell

So, if the equation is 2x X 4 = 100, will I always take the 100 and divide it by the number that was originally multiplied to get 100? In this case 4.

Yes, basically. You want to solve for the 'x', so you want to isolate it on one side of the equation and do appropriate add/subtract/multiply/divide until it is my itself.

Here is a slightly more complex example.

2x X 4 + 5 = 85

We want to simplify and getting rid of the "+ 5" on the left means that we subtract 5 from both the right and let sides of the "=" sign.

2x X 4 + 5 - 5 = 85 - 5
2x X 4 = 80

Now, just to simplify more straightforward, note that 2x really means "2 times x" so we can rewrite this as

2 X x X 4 = 80

Let's multiply the 2 and the 4 so we get 8

8 X x = 80

Now divide both sides by 8

x = 10.

Is simplifying necessary in all equations?

[markem]

Originally Posted by Darrell

Is simplifying necessary in all equations?

At this level of mathematics, it is a good thing to do. Here, we simplified in order to find out what the value of 'x' was, which is what we wanted.

Once you get to more complicated equations, you won't be able to immediately simplify to get an answer. Equations with more than one variable (the famous 'quadratic equations' of high school math are an example), you will put the equations into a certain form and then use a formula to solve the equation (more memorization ). Some times, the equation has more than one (!) answer, even in algebra, but work these things one step at a time.

btw, I didn't mention it before, but if you call your local community college or college/university, they may have someone who can help you plan out what you need to work on. At least up where I'm at, they will do this at no charge (in the hopes that you'll take a class - and pay tuition - from them).