T Nation

Can You Guys Help Me with Math?

i have this test i have to submit today (we do it online) and i swear when we go to class we only talk about like 1 thing then on the quizzes and homework theres all this stuff that we’ve never gone over so im left with my thumb up my butt.

the shit that confuses me the most right now is trying to differentiate between a negative sign and a subtraction sign, i thought you were supposed to use captions to indicate a negative but this thing never does. i also dont understand what the reasoning behind changing a minus sign to an addition sign or vice versa is for example ill have something like idk,

7(5 - 6x) - 5(9 + 8x) = 15x - 9

i get you have to use distributive and get

35 - 42x - 45 + 40x = 15x - 9

but then the way they set it up im left unsure if the - signs are indicating they want me to add or subtract and then when i start to combine like terms the way i do it vs the way its supposed to be done will differ because of the addition or subtraction confusion because sometimes it changes.

so itd be like,

35 + -45 - 42x + 45x = 15x - 9

then im guessing its like

-10 - 87x = 15x - 9

+10 +10

-87x = 15x - 19

but it already looks fucked up from this point…er

so idk, im kinda lost over here any help to explain wtf im supoosed do with those type of problems would be appreciated.

35-42x-45-40x = 15x - 9

-10 - 82x = 15x - 9
-67x = 1

x = -1/67

That’s what I get and it checks out.

Ask drivethruhero. He is the math wiz from the beast awakens thread.

[quote]hoosegow wrote:
35-42x-45-40x = 15x - 9

-10 - 82x = 15x - 9
-67x = 1

x = -1/67

That’s what I get and it checks out.[/quote]

Ditto, that’s what I got.

i guess its not that bad, to my luck the test has been postponed for like an extra 5 days. probaly cause its about a whole bunch of stuff weve never gone over and we’re already behind (cause theres some people who dont understand fractions, terminating division aaand this guy gave us a 20 minute lecture on why you need to differentiate between capital and lowercase variables), but its anyones guess.

i wonder if my inability to add and subtract could have something to do with it lmao

You have +40x in your original that should be -40x (i think). Here’s a detailed explanation. You’re welcome.

Simplifying
35 + -42x + -45 + -40x = 15x + -9

Reorder the terms:
35 + -45 + -42x + -40x = 15x + -9

Combine like terms: 35 + -45 = -10
-10 + -42x + -40x = 15x + -9

Combine like terms: -42x + -40x = -82x
-10 + -82x = 15x + -9

Reorder the terms:
-10 + -82x = -9 + 15x

Solving
-10 + -82x = -9 + 15x

Solving for variable ‘x’.

Move all terms containing x to the left, all other terms to the right.

Add ‘-15x’ to each side of the equation.
-10 + -82x + -15x = -9 + 15x + -15x

Combine like terms: -82x + -15x = -97x
-10 + -97x = -9 + 15x + -15x

Combine like terms: 15x + -15x = 0
-10 + -97x = -9 + 0
-10 + -97x = -9

Add ‘10’ to each side of the equation.
-10 + 10 + -97x = -9 + 10

Combine like terms: -10 + 10 = 0
0 + -97x = -9 + 10
-97x = -9 + 10

Combine like terms: -9 + 10 = 1
-97x = 1

Divide each side by ‘-97’.
x = -0.01030927835

Simplifying
x = -0.01030927835

Math is fucking crazy stuff.

If you never heard of “BEDMAS”, it can help you out with these questions when it comes to simplifying.

B - brackets
E - exponents
D - division
M - multiplication
A - addition
S - subtraction

So you start with brackets first then work your way down the list until everything is simplified.

It sounds like you don’t understand the objective of the problem. So here’s a general strategy for these types of questions:

  1. use BEDMAS to simplify the expression. Basically you want to get rid of the brackets like you did first, which is good. Just pay attention to your negative signs.

  2. Collect “like terms” and simplify. 35 and -9 can be simplified, same with the x’s.

  3. Now, depending on the question, you need to solve for x. In this case, your end result is to “isolate” the x term. Get x by itself, basically. It will probably be a fraction.

  4. Verify your answer for x by plugging it into the original equation:

7(5 - 6x) - 5(9 + 8x) = 15x - 9

LHS = RHS
If everything is ok, then the left hand side should equal the right hand side.

So in your head just always remind yourself something along the lines of: bedmas, simplify, like terms, isolate, verify.

Hope that helps

x=-1/97

I would do averagely well in maths, but by the time I got to finals all I did was practice for 6 hours+ a day for weeks before and I got a A.

You just got to practice maths, once you understand the rules they are quite simple to apply.

Just wait until you get to Calc. Derivatives FTW!

ummmmmm no, after this i do college algebra…which i hear is actually easier, and then its it. im not an engineering or computer major so i dont need to advance that far in math requirements.

i dont think its good to talk negatively but im just having a hard time wrapping my head around the difference between negative versus minus signs and why you have to change them to addition magically.

like im not stupid i just think sometimes things get over complicated for no reason like for example the other day he put on the board m = -1 then he puts up this rediculous forumula to determine -m = 1 and im like wait, why do you have to do all that? if m = -1 then obviously -m = 1

hes like yeah, but not everybody can just do that. i mean if you cant figure that out on your own how is making a 3 step process going to make things easier?

idk is it just me?

Wait until you get differential equations and partial differential equations. Go mathematica!

[quote]LiveFromThe781 wrote:
ummmmmm no, after this i do college algebra…which i hear is actually easier, and then its it. im not an engineering or computer major so i dont need to advance that far in math requirements.

i dont think its good to talk negatively but im just having a hard time wrapping my head around the difference between negative versus minus signs and why you have to change them to addition magically.

like im not stupid i just think sometimes things get over complicated for no reason like for example the other day he put on the board m = -1 then he puts up this rediculous forumula to determine -m = 1 and im like wait, why do you have to do all that? if m = -1 then obviously -m = 1

hes like yeah, but not everybody can just do that. i mean if you cant figure that out on your own how is making a 3 step process going to make things easier?

idk is it just me?[/quote]

Think of it this way: subtracting is only adding by a negative. So, whenever you have something subtracted in an equation, rewrite it. EX. 7-x -> 7+(-x)

3-dimensional integrals over complex shapes = brain melt

i had that in second year applied math

That is some really easy stuff man. What grade are you in?

[quote]Thomas Gabriel wrote:
That is some really easy stuff man. What grade are you in? [/quote]

That is a little harsh, but I agree. I would try to get a tutor or get one of your classmates to help you out if you are struggling with this problem.

Doing practice problems will help too. It will get so automatic you won’t even believe you ever thought this stuff was hard.

I think you are making it a lot harder than it needs to be.

my bad. added instead of subtracted 15x.

I could be different, but I’ve found it easiest to try not to “visualize” a lot of math concepts. Most of the time when you are younger you try to learn by imagining something either visually or geographically but that has always messed me up for some reason.

I’m no whiz but I will graduate this spring with a degree in applied mathematics from pretty good school; been on the dean’s list every semester.

I’ve found with math, it’s best to just “trust the numbers.” You can pontificate on why a negative times a negative is a positive, or you can just trust that it is and get on with your life and learn the concept to get what you need out of it.

[quote]Kreal7 wrote:
Doing practice problems will help too. It will get so automatic you won’t even believe you ever thought this stuff was hard.[/quote]

Second that. For instance, when you are first doing any sort of physics that involves calculus, the line integrals get real confusing. After a couple years of doing them in various forms for various classes, they get real easy.

That’s just how math is; I’ve always been into various card games and I know dudes who didn’t graduate from high school who can do some pretty hardcore probability calculations in their head, just from being around games where they had to calculate odds for 20 or 30 years.

Guess it’s like anything in life, the more you practice it, the more familiar you get with it and the easier it gets.