Author Topic: Math help  (Read 1729 times)

Backward/reverse solving.
When you have an equation you work on it piece by piece backwards, you do the same to both sides of the '=' sign, this includes reversing BIMDAS/BIDMAS so that + and - come before multiplications and dividers.
This means you work in reverse of the equation to find the original starting factor (x)
e.g. 9(x-8)+3=-15
Start by getting rid of the brackets so you have a simple equation.
9x-72 + 3 = -15
Now we work backwards to get rid of that +3, to do so we take 3 away from both sides, so we get
9x - 72 (the +3 is now gone) = -15 -3 (remember that whatever you do on one side you do to both, making this -18)
Now to get rid of the -72, we add +72 to both sides
9x (72 is eliminated) = -18 + 72 (54)
Now all we have is 9x=54
For the final step, 9x is saying it is x multiplied by 9, to work backwards we divide both the 9x and the 54 by 9 so we get
x=6

Wow I really have nothing better to do with my time, do I? Oh well, these types of equations are without a doubt the easiest to learn, you will pre much have a 100% chance of getting them all right on a test once you understand to just do the entire equation in reverse.

wouldn't you combine like terms
-72 + 3 = -69
-15 + 69
and so on

I cant get this one.
7(x-8)+19=-16

I cant get this one.
7(x-8)+19=-16

7x-56+19=-16
7x-37=-16
+37 37
7x=21
X=3

wouldn't you combine like terms
-72 + 3 = -69
-15 + 69
and so on
You can, I am just doing as my old math teacher and explaining the long process, when put into practice I skip all of those steps and either go straight to the answer or have one line between, but even if you do that it is helpful to know the simplest/more spread out way to do it, whether or not you intend to use it.

9 (x - 8) + 3 = -15

9x - 72 + 3 = -15

9x - 69 = -15

9x = 54

x = 6

This is like elementary algebra dude. I'd be ecstatic if this was my homework.

« Last Edit: October 15, 2012, 02:58:51 PM by Magnusbon »

This is freaking easy, how can you have problems doing this

Dear Algebra;

I'm tired of finding your X. Just accept the fact that she's gone.

Move on, dude.