Algebra problem help!

I've been stuck on a problem and recently got further into it and now I'm stuck again and I really need help.

3 = 10x - 3x^2

What step do you take in order to subtract that?

Huh? Are you asking from a programming point of view, or just in general, or what?

Homework...

You find operations which - when applied to both sides of the equation - get the equation closer to what you're trying to find.

For example:

10 = X + 4

Subtract 4 from both sides of the equation.

10-4 = X + 4 - 4

Simplify

10-4=6
4-4 =0

Therefore

6 = X

Or

X=6

?
3 = 10x - 3x^2

you want to know how to subtract 3x^2 from 10x?

if x is 2...

10x - 3x^2
10(2) - 3(2^2)
20 - 3(4)
20 - 12 = 8
?

be more specific?

I have to solve for "x"
The problem starts out as
x+(1/x) = 10/3
I know the answer is 3 but I just don't know how to get to it

x = 3, just from looking at it..


3 = 10(3) - 3(3^2)
3 = 30 - 27
3 = 3
True

edit: saw you knew, well, I forget actually, i'll have to look that up, i'm curious too

EDITED:

On second thought, I think you do a factor

3 = 10x - 3x^2
that would be -3x^2+10x-3=0

Then you work it from there
of course it probally wont work, I did this soooooo long ago.

I hate algebra, I like geom/trig much better

I hate algebra and geom, Geom is boring and algebra is evil, Trig owns all.

Well my dad ended up with 3x^2-10x+3=0
= (3x-1)(x-3)=0
= x = 1/3
or x = 3

your in algebra, do you have a text book? if so, tell us, I hate not knowing something I know I don't know (does that make sense?)

Yes. Yes... I do that a lot

The first step is to rearrange it to the form Ax^2 + Bx + C = 0. Here we get 3x^2 - 10x + 3 = 0.

As you learn to solve these the three basic methods are:

1. Guess.
2. Try to factor.
3. Use the Quadratic Formula.

The appropriate one for homework would be whatever you've been doing in class recently.

3 = 10x - 3x^2

Subtract 3

-3x^2 + 10x - 3 = 0

Multiply by -1

3x^2 - 10x + 3 = 0

Now there's two ways to solve this. I'll show you both.

1) FACTORING

When you see the equation set up where it's ax^2+bx+c=0, it's usually a clue you can break it apart into two parenthesis that, when multiplied out, equal zero. This problem was no different as I was able to do so like this:

(3x-1)(x-3) = 0

Because you're solving for x, you have to figure out what makes each of the parenthesis 0 because that's what they're equal to. That would of course be 1/3 and 3. If you fill those numbers in for x in the original equation you'd find that only 3 works. Thus 1/3 is not a valid answer.

2) QUADRATIC EQUATION

You take the equation we started with, 3x^2 - 10x + 3 = 0, and because this is set up as Ax^2 + Bx + C = 0, then:

a = 3
b = -10
c = 3

Now take the quadratic formula. For a picture of what it looks like, and an online calculator to solve it for you, visit http://www.1728.com/quadratc.htm

If you fill it in with the a, b, and c in this problem, then you get the answers of 3 and 1/3, just like when we factored it. 1/3 doesn't work once again so 3 is still your answer.



Fun, eh? :D Hopefully I answered your questions.

Awe thanks. My book did teach how to do it like that where
LeftSide = 0

But after that, I never used that way.

Well... I know it's been solved alot already.

But it can be rearranged to be
3x^2-10x+3=0

Factorise is it to

(3x-1)(x-3)=0

And there for

X = 1/3
or
X = 3

No need for the quadratic forumla on this one.

Yeah, but I showed him both because he may get a problem in the future where it can't be factored and he has to use the quadratic formula.

quadratic formula is easier :)

No it isn't.

Now I know why I hate algebra. Trig is much more fun, more angles shapes and stuff.

Ah fair point.



It's easier in the sense you can just plug in numbers, but being able to factorise like that means you can do alot of the stuff in your head which is pretty damn useful. But both are important to know

To the original poster, I am not sure what the purpose of the question was however if it was from an education standpoint. Might also be worth you having a look at a method of solving quadratics called "Completing the square".

It is the general way to solve second degree equations, so you must learn it sooner or later.

It can be. All you do is plug numbers into a formula and test what the formula gives you in the original equation.

Factoring on the other hand, can get pretty complicated at times. For a problem like this it was fairly easy, but some times it can be pretty hard to get it.

i find it kinda funny that it took this many posts to solve one equation! :D (im not saying i know how to solve it! :D:D)