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Im not really the one to ask, but this is pretty complicated to me.
You guys know about the 'system of equations' and the 3 ways to solving them, right?...
1.graphing
2.substitution
3.elimination
Well I need some help with substitution..
When its something like this...
y=2x
and
y=3x-2
or
y=x
y=2x-4
What exactly do you do?
Yeah, I took notes on it in school, but its still pretty fuzzy in my head.
Help is much apreciated. =/
O my god, this is easy. I can't explain it by typing but what grade are you in? I learn this in 7th grade.Quote:
Originally Posted by Jakuza
What grade you in? Anyway, I just got a 98 in advanced pre-al, so maybe I can help. :PQuote:
Originally Posted by Jakuza
We just did this shit last week. We'll use this.
y=x
y=2x-4
So take y=x for example, or x=y. Now, if x=y, let's substitute in for the x variable in the second equation. So y=2(y)-4, y=2y - 4, -y = -4, then y=4. Now, to find x, let's substitute again. Go back to y=x. Substitue y for 4, leaving you with 4=x. So your solution is (4,4). Then check:
4=4 (correct)
and
4=2(4)-4
4=8-4
4=4 (correct).
There ya go.
GOOD JOB man, give your self a high five for just telling him the answer and not letting him figure it out on his own. I lost all respect for your jakuza, I thought you were smarter than this. That equation was just child's play.Quote:
Originally Posted by KCBlack
Well, im not exactly a fast learner, let alone an average learner.
O well, you will learn. I was like that when I was young.Quote:
Originally Posted by Jakuza
...Just when I thought you couldn't be more ******ed.Quote:
Originally Posted by laughingman112
I see that KCBlack already explained it, but I'll try explaining it again in case you still don't understand.
Lets take the first problem. I suggest solving these by substitution because it's the easiest.
You see that Y is 2x, and it's also 3x-2. Therefore, 2x would equal 3x-2. If something equals something, and it equals something else; both those things will equal each other.Quote:
y=2x
y=3x-2
For example.
5=3+2
5=1+4
So, 3+2=1+4. Get it?
After you figure out what 'x' is, plug it into one of the equations to find out what 'y' is. Then you should always double check.
Whenever you see a y="equation", and another equation has a 'y' in it, you can substitute that 'y' for the equation. If you still need help, read the section in your book and do some extra problems.
Durr......Quote:
Originally Posted by Xynh
Im not really the one to ask, but this is pretty complicated to me.
You guys know about the 'system of equations' and the 3 ways to solving them, right?...
1.graphing
2.substitution
3.elimination
Well I need some help with substitution..
When its something like this...
y=2x
and
y=3x-2
or
y=x
y=2x-4
What exactly do you do?
Yeah, I took notes on it in school, but its still pretty fuzzy in my head.
Help is much apreciated. =/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dont you just simplify by combining them.
so if it was
y=x and y=2x-4
then x+2x-4
|
3x-4
oh wait wait
your doing graphs and etc huh?
so there would be two equations....
you dont do nothing then man its just two seperate variables for two different equations
Well thanks, you guys. I think I got the pure concept now. Did 3 on my own just a minute ago. I solved and checked it, and they came out correct. =]
thx to raikun09's 1337 skills in geometry............and those other guys>_>
This is algebra, my brother. :pQuote:
Originally Posted by raikun09
Lmao. Glad you got it. I didn't get substitution at first either. Of course, I NEVER pay attention in math and relearn anything I don't get when I get home.Quote:
Originally Posted by Jakuza
Jakuza, if you don't get subsitution you could use elimination. Which is like the same concept but I found it alot easier.Quote:
Originally Posted by Jakuza
Correct me if I'm wrong, but elimination works best if the numbers are the same.Quote:
Originally Posted by laughingman112
For example. If I got a problem like
y=2x+5
y=3x-5
Then I'd use elimination to do it because it's much easier. But life doesn't always give you problems that are that easy to do. I still suggest using substitution because you'll be using it a lot later on, plus it'll work with almost every problem.
It's been a long time since I've done anything like this so do correct me.
It depends on the equation. Sometimes its faster an easier to use substitution than elimination, and vice-versa.Quote:
Originally Posted by laughingman112
Graphing was always easy for me... Infact I laughed when the teacher was explaing y=x and he said when x = 4 than y = 4 and this girl in the class just did not understand why. The teacher was practically yelling at her, and I couldn't really blame him.
The only trouble I had, and still have, is with word problems. When messing with just numbers I can usually crunch it out. But eventually you get into math where you just have to remember about a billion different forumulas, and some formulas only work on certain equations and with certain equations you have to something just a little different...
Math is lame.
hmm i dun rememeber this i think i was sleepin in class that day
The substitution one is piss easy. I can't do elimination though. I did learn, but i wasn't paying attention.
Y=3x-4
Y=2x+5
Find out the X by doing the following:
3x-4=2x+5
3x-2x=5+4
x=9
Now if you substitute the x for 9:
Y=3x-4 = 3(9)-4 = 23
Y=2x+5 = 2(9)+5 = 23
There you go.
Elimation only works is you can get either same X or same Y. So for exampleQuote:
Originally Posted by Ramstien
Y = 2X + 5
Y = 3X - 5
--------------------
(First you need to make the X's equal... the common numerator is 6 hence)
3Y = 6X + 15
2Y = 6X - 10
------------------------
(Now to elimante X we need to make either the top or bottom negative)
3Y = 6X + 15
-2Y = -6X + 10
-------------------------
Y = 25
(The math is simple, just add)
So knowing that (Y = 25) we plug why back in to either Equation
25 = 3X + 15
10 = 3X
X = 3/10
Simple...
Hardly. If anything, i un-learned.Quote:
Originally Posted by Sandman53
What the, how old are you guys? In Singapore we learnt this last year in our 8th Grade, 14 years old. o_O This year all our maths involves algebra lol...
K what you need to do everytime is to make x the subject, that is, to make it alone. First you just make one of the variables alone and substitute it into the other equation, so the equation will only have one variable then you can just bring the numbers over and solve it.
For example:
y = 2x + 5 - first equation (1)
y = 3x - 5 - second equation (2)
Sub (1) into (2)
2x + 5 = 3x - 5
Bring 2x from the left to the right, so it'll become -2X
5 = 3x - 2x - 5
5 = x - 5
Bring -5 to the left so when it moves over the '=' sign it will become +5 right?
10 = x - third equation (3)
Sub (3) into (1)
y = 2(10) - 5
y = 20 - 5
y = 15
Voila solved.
y = 2xQuote:
y=2x
and
y=3x-2
y = 3x - 2
Just substitute the first one into the second equation so you'll have
2x = 3x - 2
bring 2x over
0 = x - 2
bring 2 over
x = 2
Donez!
y = xQuote:
y=x
y=2x-4
y = 2x - 4
x = 2x - 4
0 = x - 4
x = 4
Have fun with algebra! lol...
Quote:
Originally Posted by Raiyne
9th grade, Algebra (H). O_o
His asking for help, give the guy a break. Im pretty sure everybody had ask for help before.