MATHFAGS please help

[sans culottes]

Tomorrow is my third day of school, and I've hate to fail my first homework assignment. I tend to make a B average in regular math classes, but I'm still kinda shitty with algebra. My homework is a review of Algebra I stuff, and I barely remember any of it.

Please, help me with these questions, and me love you long time.

1) Solve for x: (x-2) - 2(x+4) = 3(2x-3)
2) Solve for x: 2(x-2) = 3(2x-3)
3) Solve for x: 2x - 5 + 3x - 10 = 90
4) Solve for x: x^2 - 5x - 14 = 0
5) Solve for x: x^2 - 2x - 24 = 0
6) Solve the system: { x + 5y = 17
_________________{ 2x + 3y = 13
7) Solve the system: { 2x + 3y = 5
_________________{ x + 2y = 4

That's the first half of the questions on my assignment. What I aim for is to recall all those systems and formulas that I forgot. Some of you might think I'm a dumbass for not understanding this, but oh well. I spent most of Algebra I in my freshman year having weird conversations with two stoners and I barely passed it, so I seriously gotta learn this.

[Mando Pandango]

Alright, first thing you want to do is isolate simplify all of the terms. I'll use problem 1 as an example.

(x-2) - 2(x+4) = 3(2x-3)
x-2 - 2x-8 = 6x - 9
-x - 10 = 6x - 9

Then you get get x on one side

-x - 10 = 6x - 9 (add 9 to each side)
-1 = 7x (divide each side by 7)
-1/7 = x

Any questions?

EDIT: Oh you also have polynomials and systems. Gimme a sec.

[sans culottes]

So, is that how distribution would usually work? When you have somethign like 2(x+4) you get 2x and 8?

[Mando Pandango]

So, is that how distribution would usually work? When you have somethign like 2(x+4) you get 2x and 8?

You multiply the number on the outside of the parentheses with each term inside of the parentheses. 2 * x = 2x, and 2 * 4 = 8.

If the number on the outside is negative or has a minus sign in front of it, like this.

1-2(x+4)

The negative carries through, like this.

1 - 2x-8

[Mando Pandango]

4) Solve for x: x^2 - 5x - 14 = 0

This is a bit trickier. If you remember the FOIL technique, it's basically undoing that. If you don't, it's when you see something like this:

(x+4)(x-8)

and multiplying the terms to get something like you see in the problem. You multiply the Firsts, Outside terms, Inside terms, and Last terms, hence FOIL

F: x * x = x^2
O: x * -8 = -8x
I: 4 * x = 4x
L: 4 * -8 = -32

so

(x+4)(x-8) = x^2 - 8x + 4x - 32 = x^2 - 4x -32

So basically, we're given the end product and we need to go backwards. The problem is:

x^2 - 5x - 14 = 0

Since it's x^2 with no coefficient, we know both sets of parentheses start with x.

(x  )(x  ) = 0

Now since the last number is 14, we need to find two products of -14 that when added together make -5. In this case, it happens to be -7 and 2. So that's what we fill in the parentheses with.

(x-7)(x+2) = 0

Then, we solve each set of parentheses for 0. We do this because since anything times 0 = 0, if one of these = 0, the equation = 0.

x-7 = 0, x+2 = 0
x = -7, x = 2

Yep, you get two answers, and they're both right. So that's that. Any questions here?

[sans culottes]

Right, right, I'm starting to get this. I posted a system - how do I do that?

[Mando Pandango]

6) Solve the system: { x + 5y = 17
_________________{ 2x + 3y = 13

I was getting there. I'm doing these one at a time to make sure you get them. This actually isn't too bad. What you do here is you take one of the equations for x or y. I'll be solving the first equation for x.

x + 5y = 17
x = 17 - 5y

Then you plug that in for x in the second equation

2x + 3y = 13
2(17-5y) + 3y = 13
34 - 10y + 3y = 13
34 - 7y = 13
-7y = -21
7y = 21
y = 3

Then we use that to plug 3 in for y in the first equation

x + 5y = 17
x + 5(3) = 17
x + 15 = 17
x = 2

So, x=2, y=3.

[sans culottes]

Mk, I tried the other system on my own.

I got:

X = 1.375
Y = .75

Is this correct?

[Mando Pandango]

You can test these yourself by plugging your answers back into the original equation.

Sorry but it looks like that's not it.

[sans culottes]

Then it appears I must rework it.

I'm about done with this homework, thanks!

[Feynman]

Jesus Christ, how old are you?

[rdl]

don't be a jackass.

im guessing he's a junior if he took algebra freshman year.

[sans culottes]

Jesus Christ, how old are you?

I'm a junior but I've forgotten pretty much everything about algebra. I needed help with all those formulas before I could go figure on my own.

Yeah, that's right, I'm part of the majority of students who make B's in regular math classes.

[Travis]

I'm a junior but I've forgotten pretty much everything about algebra. I needed help with all those formulas before I could go figure on my own.

Yeah, that's right, I'm part of the majority of students who make B's in regular math classes.

i got an F on my math final last year

[Feynman]

don't be a jackass.

im guessing he's a junior if he took algebra freshman year.

It's ridiculous.