Multiple Step Equations.....help Please

[Barbies are Evil]

gah, why can't I understand this? sometimes a - indicates a negative number and sometimes it just equals subtracting a positive number.....gah! I don't know whats wrong, I get stuck on one step and then the equation doesn't make sense anymore....gah! (plus i'm in special ed math, so REALLY simple explinations would be appreciated) i'll throw a few problems out there.....and please, I don't need just the answer, I need help on how to do it.....



problems: -2(6+a)-a=-18

2t-(3t+7)=9

5m-(m-7)=-1

[jess_617]

-2(6+a)-a=-18

Step 1: -2 times (6+a)..........-12-2a-a=-18

Step 2: combine like terms....-12-3a=-18

Step 3: subtract -12 from both sides...-3a=-6

Step 4: divide both sides by -3...a=2



2t-(3t+7)=9

Step 1: -1 times (3t+7)....2t-3t-7=9

Step 2: combine like terms...-1t-7=9

Step 3: subtract -7 from both sides...-1t=16

Step 4: divide both sides by -1....t=-16



5m-(m-7)=-1

Step 1: -1 times (m-7)....5m-m+7=-1

Step 2: combine like terms....4m+7=-1

Step 3: subtract 7 from both sides...4m=-8

Step 4: divide both sides by 4...m=-2







alrighty...those SHOULD be right. I checked them and they turned out right so there you are.

[Barbies are Evil]

gah, I still don't understand.....

[SirPostAlot]

I'll try to make it simpler but jess explained it very well...



Problem A: -2(6+a)-a=-18



You have to notice that -2(6+a) is ONE number in this part because of the parenthesis...

So you use the digstributive property:



-2 times 6 = -12

-2 times a = -2a



So it would be: -12-2a-a = -18



You can add the negatives (so you would be actually subtracting -2a -a) getting -3a...



-12-3a = -18



Then you want to get rid of the -12 on the left side, so you add 12 to both sides of the equation (what you do to one side you have to do to the other)

so you get:

-3a = -6



then you divide both sidees by -3, so you get a = 2 *a negative divided by a negative is positive because they would cancel out*



so you get a = 2



problem 2: 2t-(3t+7)=9



This one is similar except there are 3 numbers: 2t, -1(3t+7), and 9



so you again use the digstiributive factor:



-1 x 3t = -3t

-1 x 7 = -7



so you get 2t-3t-7=9

then you have a positive 2t and you subtract 3 t...



Think of it this way...you have $2 to your account but your friend wants to borrow $3 from you, so you have to borrow $1 from another friend to pay off your friend...so you have -1$ in your pocket...



so 2t-3t = -1t...



-1t-7=9



add the 7 to both sides...



-1t=16



divide both sides by -1 and you get t=-16





Problem 3: 5m-(m-7)=-1



Again you have three numbers: 5m, -1(m-7), and -1



Again do the digstributive factor:



-1 x m = -1m

-1 x -7 = 7 *a negative times another negative is positve*



so you would have 5m-1m+7=-1



So in this case you have $5 and your friend asks you for $1, so you have $4...



So you would have 4m+7=-1



Subtract 7 from both sides, -1 -7 = -8



*You owe $1 to your friend and you borrow another $7, so you owe $8...



so you have 4m = -8



Divide both sides by 4 and you get m = -2





they match jesses...haha...





Does that help?



~Jeff~

[Barbies are Evil]

that I actually sorta understood Jeff

[SirPostAlot]

Really? Aww thats good hun, i try to help



If you have any additional problems, just post them and i will try to help...



Usually when i try to help people i get them all confussed...haha....











~Jeff~

[Paris In Flames]

Originally posted by SirPostAlot@May 9 2005, 05:37 PM

Really? Aww thats good hun, i try to help



If you have any additional problems, just post them and i will try to help...



Usually when i try to help people i get them all confussed...haha....











~Jeff~

[right][/right]

Wow, that's crazy. You explained that pretty well. I seriously don't ahve the patience for that. I don't understand why kids DON'T get it.



Alas - I will never be a teacher.



Cheers,



Jenna

[SirPostAlot]

I would never be a good teacher...

Things like this i can explain but i do things differently then other people...

One time my chem. teacher came up to me and asked me to help a frined out to study for a test becuase the teacher had a bazillion things to do and she thought i could help...so i helped a friend out for studying for chemistry and she ended up getting a 52% on the test becuase she said she understood my way of doing things but i guess she didn't



Luckly, the chem teacher is my academic decathlon coach and she knows my personality and my crazy way of doing things, so she helped my friend and let her re-take the test...haha



So i wouldn't make a good teacher either



~Jeff~