I am reviewing math in the back of my physics book and I don’t have a college algebra book anymore. I tried goggling this for 2 hours or so and could not find anything similar. It seems like it’s a certain type of problem giving me problems.
Two problems I have the answer to both but cannot figure out how they came up with the answer.
Solve for x
ax – 5 = bx +2 Answer is: x = (7/(a-b))
I cannot figure this out I moved the 5 over that’s easy
ax = bx + 7
I then tried to move the “bx”
ax – bx = 7
I then divided 7 by -b
ax –x = (7/(-b))
I then divided by a
x – x = (7/(a-b))
However would not x – x = 0
I must not be getting some rule…. Even if when I moved the negative b over if I didn’t leave a neg it would be x +x which would = 2x
Right? I am confused on this and the other one I had problems with Is similar.
A = (1/(1+x)) Answer is x = ((1-a)/(a))
I think these are related because this one also I could not solve this one either… I solve all the normal x stuff but it has to be a rule I am missing…
I think I figured out the second problem as listed below I left it in just in case I made a mistake.. I have taken College Algebra, Trig, Calculus I but that was back in 1997. I am now enrolled in Engineering Physics, and Calculus II which start next week so trying to review and catch up and review stuff on my own before I am really hazy on this stuff so forgive any seeming ignorance on my part. I may be posting a lot of questions on here in the coming weeks. Next week I will have access to school tutors as well and I should be getting in my Calculus I, and II MathTutorDvD I ordered from a website... hopefully they are good if so I will order Calc III and Physics CD from them as well. I use to be really good at math but not feeling so good at it right now
a = (1/(1+x))
took (1+x) and since I was dividing I did the opposite and multiplied by both sides
a(1+x) = 1
I think that then breaks down to
1a + ax = 1
I then did opposite moving 1a over
ax = 1 – a (since “a” and “1a” are the same thing I just took labeled it as “a”)
I then divided by a
X = (1- a)/(a)
I don’t know why I got confused on that one now it seems easy
So its just that first one I am having a problem with ugggg I hate not being able to figure out something I will almost go till my nails are fingers are bleeding and I fall over in the chair from exhaustion lol. Learning to put things away to come back a different day is very hard for me lol
Alright with the first one, what you did initially was correct, so I am going to start with
ax – bx = 7
What you need to do next is realize that both (ax) and (bx) have an (x) term, so you can factor
ax - bx into x(a-b) I think that is the confusing part. once you do that
x(a-b) = 7, simply divide both sides by (a-b)
Wow... that was fast...
I have a question though...
I am not sure I understand this:
Is there any documentation on now this works or what its called. I am trying to remember this but its not striking a bell.
I understand looking at it that x(a - b) = 7 is the same as xa - xb = 7
but I dont remember pulling an x out like that. (btw is that algebra I, II, or College Algebra? (my terminology is going to be yuck for awhile lol)
Hey thanks a ton for the prompt answer I am so glad I found this forum!
Sincerely,
Brian
Ok I think S31J41 answered the second part of my question... I am so relieved I tried figuring that out for hours...
So thats called factoring out and that definitely sounds familiar and I am starting to recall a tad bit about that. Also can now maybe do searches on it if I need to.
Guys are awesome thanks!
Sincerely,
Brian