Author Topic: Math help (Read 10794 times)

ex · « **on:** July 23, 2012, 06:34:29 PM »

I'm calling upon the math whizzes of the community, as I'm trying to study up for an upcoming test to pass so I don't get placed into fucking bullshit remedial math classes at college. There's a few things I'm rusty as hell on and/or forgotten completely how to do over the years.

The main thing is factoring. I'm really having a time trying to remember how this works, so anyone who knows help me out!

BTW, the problem I'm trying to solve looks like this:

x^2-x-6
x^2-4

with an equals sign after the problem.

I know the answer is:

x-3
x-2

...but I have no clue how to get there. Any help would be greatly appreciated!!

p.s.: I might add more topics as I go, but for now factoring is the only one that's truly fucked me up as I can't remember at all how to do it, or where to start.

metaL · « **Reply #1 on:** July 24, 2012, 04:32:46 AM »

(x-3)(x+2) (x-3)
======== =====
(x+2)(x-2), The (x+2)'s cancel out, leaving you with (x-2)

x^2 - x - 6 becomes (x-3)(x+2) by first looking at the last value (integer) without a variable (-6). You need 2 multiples of -6 that can be added or subtracted to get your x value value (-1, since it's -x). I'm not great at explaining stuff but in this case it's 2 and -3. 2 x -3 = -6 and 2 - 3 = -1.

(x-3)(x+2) = x^2 + 2x - 3x -6 = x^2 - x - 6 multiplied out

x^2 - 4 becomes (x+2)(x-2). There is no x value, so the multiples of the integer value you have to use must be added or subtracted to zero (2 and -2 in this case)

(x+2)(x-2) = x^2 + 2x - 2x -4 = x^2 - 4 multiplied out

soh · « **Reply #2 on:** July 24, 2012, 06:20:32 AM »

Out of curiosity, what is the geometry on that placement like(i.e Practice Test)? Or at least do you know?

haunted · « **Reply #3 on:** July 24, 2012, 06:23:31 AM »

Not sure what you're asking Escher, but this would be considered err... pre-cal or "college algebra".

soh · « **Reply #4 on:** July 24, 2012, 06:51:40 AM »

When you go in to take the placement exam for a college. They usually start off with the basics. Arithmetic, Pre-Algebra. Then they go into Elementary Algebra, Intermediate Algebra... and then after that they start asking Geometry questions. After that they ask Pre-Calculus stuff. And then Calculus 1, 2 questions.

I'm asking what kind of questions are there for the Geometry section on that placement exam??? Is it basic stuff like Volume of a Sphere? Simple Length x Width? Or do they actually ask you to prove things? Some schools just ask one or two questions on that exam for Geometry, and then go on with the other things.

haunted · « **Reply #5 on:** July 24, 2012, 07:02:59 AM »

I'm not used to that sort of order exactly... Geometry could come before an "intermediate algebra" level, or it may not.. depends on the school and the student. The last time I took a math placement test was in 2006, and I've already taken up to calc3 so I doubt I'll be taking many more of those... so it's hard for me to remember. BUT, you'll likely find the more difficult(and more practical) uses of geometry in the trig section(which would come before the pre-cal). Else it'll be area/volume of various things(better know your pythag theorem).

All geometry is kinda basic though, same with in the trig section.

ex · « **Reply #6 on:** July 24, 2012, 09:13:51 PM »

Quote from: metaL on July 24, 2012, 04:32:46 AM

(x-3)(x+2) (x-3)
======== =====
(x+2)(x-2), The (x+2)'s cancel out, leaving you with (x-2)

x^2 - x - 6 becomes (x-3)(x+2) by first looking at the last value (integer) without a variable (-6). You need 2 multiples of -6 that can be added or subtracted to get your x value value (-1, since it's -x). I'm not great at explaining stuff but in this case it's 2 and -3. 2 x -3 = -6 and 2 - 3 = -1.

(x-3)(x+2) = x^2 + 2x - 3x -6 = x^2 - x - 6 multiplied out

x^2 - 4 becomes (x+2)(x-2). There is no x value, so the multiples of the integer value you have to use must be added or subtracted to zero (2 and -2 in this case)

(x+2)(x-2) = x^2 + 2x - 2x -4 = x^2 - 4 multiplied out

Hey, you're not bad with explaining. I forgot that factoring is like simplifying a problem down to its rudiments. What's sad is, I remember when I was learning this shit several years back, I had the hardest time with factoring then too. Something about it fucks me up bad. I'm just gonna have to hunker down and do shitloads of these problems until I get my flow back on them.

Thanks for the help!

And to Escher, the college placement has just basic geometry on it. Pythagorean shit, radius/diameter of a circle, maybe figuring out the area of a trapezoid or rhomboid. Not too difficult of stuff, but I'm not going to retest after being rusty on it for 7+ years. lol. What's sad is when I originally started, I made one of the highest scores recorded in the reading, writing, and essay sections, but the math I basically flunked with a 40. lol...math has never been my strong point, but I guess I'm not alone. I've heard anywhere from 92% to 98% of Americans have trouble with math. Fuckin a.

soh · « **Reply #7 on:** July 25, 2012, 12:40:51 AM »

Quote from: haunted on July 24, 2012, 07:02:59 AM

I'm not used to that sort of order exactly... Geometry could come before an "intermediate algebra" level, or it may not.. depends on the school and the student. The last time I took a math placement test was in 2006, and I've already taken up to calc3 so I doubt I'll be taking many more of those... so it's hard for me to remember. BUT, you'll likely find the more difficult(and more practical) uses of geometry in the trig section(which would come before the pre-cal). Else it'll be area/volume of various things(better know your pythag theorem).

All geometry is kinda basic though, same with in the trig section.

Didn't you start off as a Math major Haunted? What happened there? Lost interest? Or, found new interests?

Aren't Physics majors supposed to take Differential Equations? You still have more math to go.

And yeah, I found myself learning more about Geometry when I was taking Trig than ever. In the Los Angeles Community College District you are required to take Intermediate Algebra and Plane Geometry before you take Trigonometry and Pre-Calculus simultaneously. I couldn't wait, so I took the exam and scored into Precalculus and Trigonometry. Sad thing is they don't make it harder than that. It's a joke! But I guess it weeds out a lot of the students who want to jump right into Precal/Trig since there are budget cuts and there aren't many classes available for everyone

I got let go from my job, so I am going to be doing school full time along with my Web Development Internship(unpaid btw(don't you

employers)

)
Whatever you guys do, stay in school!

Good luck with that placement exam ex

metaL · « **Reply #8 on:** July 25, 2012, 04:43:50 AM »

Yeah I told haunted he has DE to look forward to lol, I never took any math past calc 1. I was about to take a placement test along with like 200 other people at UNC and the guy at the podium was like "Anyone who is satisfied with their SAT 2 score's placement may leave now." I was the only person that got up and left. I had already placed out of remedial stuff and "business calc" basically an easier calc 1, and I didn't want to place into calc 2 because at the time that was the most failed class at UNC, mostly because of the teacher but also because that is the hardest math at UNC (hardest course to pass statistically, not hardest material to grasp). I was a Pre-pharmacy major turned biology. And now I'm a heavy equipment operator lol, I should have majored in engineering... I'd advise anyone with math skills to do the same (I have the most lopsided SAT scores out of anyone I know, math being awesome and verbal very shitty)... engineers get HIRED. Even when times are bad. Civil, mechanical, chemical, electrical, environmental, etc. engineers never have a lot of trouble finding a job. That's all school is good for anyway (aside from meeting people/beer/weed/pussy). Funny how I needed a degree to get my dredging job initially, then I was offered a position that paid better and took it, now I have a job that does not require a college degree lol. Oh well.

ex · « **Reply #9 on:** July 25, 2012, 05:52:00 PM »

Ok, getting the hang of it again, but this is weird:

Quote

Factor 2w^4 - 162 =

ANSWER:

1. First factor out the 2:
⇒ 2w^4 - 162 = 2(w^4 - 81)

2. 81 = 9^2 and w4 = (w^2)^2 so we can use the difference of two squares:
⇒ 2(w^4 - 81)
= 2((w^2)^2 - 92)
= 2(w^2 + 9)(w^2 - 9)

3. w^2 - 9 is another difference of two squares
= (w + 3)(w - 3)

So the final result is:

2w^4 - 162 = 2(w^2 + 9)(w + 3)(w - 3)

The only thing that confuses me is why you don't go ahead and factor it down to:

2w^4 - 162 = 2(w + 3)(w + 3)(w + 3)(w - 3)

...instead of leaving one of the answers non-factored. Some rule I'm forgetting I bet.

metaL · « **Reply #10 on:** July 26, 2012, 04:32:38 AM »

w^2 + 9 is simplified.

(x +3)^2 = x^2 + 3x + 3x + 9 = x^2 + 6x + 9

in other words addition of 2 squares is nothing like difference of 2 squares

|iR|Focalor · « **Reply #11 on:** July 26, 2012, 05:01:11 AM »

http://www.youtube.com/watch?v=gZEdDMQZaCU

Barton · « **Reply #12 on:** August 01, 2012, 05:42:02 PM »

http://www.youtube.com/watch?v=FXgV9ySNusc

^You can try those lecture math videos that are free on the web. One popular source for this online is Khan Academy. I really wish I used this resource more, when I just recently took Statistics, cause the instructor didn't teach the concepts thorough enough as he was too focused on steamrolling thru the material for our exams. Also, the $200 dollar assigned textbook was fucking useless. I can't even sell it back to my school. I only keep it because the tables it has for the statistical functions are really good.

ex · « **Reply #13 on:** August 02, 2012, 01:52:18 PM »

Factoring is hard for sure. Got a new problem now tho. I don't get this shit at all:

7 times [5^2 + 4 times (3 + 3) =

The answer says it's 1218, but when I work it down it comes to 427. I'm using PEMDAS to solve this so I don't understand why it's not working.

quadz · « **Reply #14 on:** August 02, 2012, 02:37:05 PM »

Quote from: ex on August 02, 2012, 01:52:18 PM

7 times [5^2 + 4 times (3 + 3) =

Where's the missing closing ] bracket?

If you want 1218 it'll have to be here:

7 times [5^2 + 4] times (3 + 3) =

Author Topic: Math help (Read 10794 times)

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