I'm having serious trouble adding

[K.I.L.E.R]

I think my biggest problem isn't calculus or anything but simple addition, multiplication and division.

I'm having some serious issues when it comes to adding things.

1-x^2 + 2x^2

= 1 - (2x^2 - x^2)
= 1 - 2

How can this NOT be right?

AFAIK 2x - 2x^2 = -x

 

[Dersaidin]

1-x^2 + 2x^2

I'll write that differently

1-(x^2) + 2(x^2)
1-1(x^2) + 2(x^2)
1 + (x^2)
1 + x^2

 

[K.I.L.E.R]

x^2 + 2x^2 = 3x^2?

Sorry.

-x^2 + 2x^2 = 2x^2 - x^2 = 2 - 1 = x^2
1 + x^2?

Thanks.
Can someone give me examples of more advanced algebra?

1-x^2 + 2x^2

I'll write that differently

1-(x^2) + 2(x^2)
1-1(x^2) + 2(x^2)
1 + (x^2)
1 + x^2

 

[Moloch]

you guys with your crazy math make me

 

[K.I.L.E.R]

I've been doing first order ODE and I keep getting similar results as the answer sheet states.

The thing is, only 4/40 of my answers are an exact match to the answer sheet's results.
The rest are off by a few numbers.

 

[Sage]

-x^2 + 2x^2 = 2x^2 - x^2 = 2 - 1 = x^2
1 + x^2?

-x^2 or -(x^2) ?

there is a difference, you know...?

 

[Xmas]

-x^2 or -(x^2) ?

there is a difference, you know...?

Well, no. Writing -x² is equivalent to -(x²). (-x)² is different.

 

[Sage]

Well, no. Writing -x² is equivalent to -(x²). (-x)² is different.

err... that's what i was thinking... oops...

 

[AlNom]

Can someone give me examples of more advanced algebra?

How about Schrodinger's equation?


But seriously, how about pulling out a question from your textbook that you think you'd have trouble solving? Thinking up math questions was never part of our (at least my) curriculum, only solving.

And you're only dealing with first order, right?

 

[K.I.L.E.R]

I'm doing 2nd order now.
I know how to do them though I just hope that I don't forget anytime soon.

 

[AlNom]

Ah, so you've gotten to the "guessing" of solutions with sine/cosine/exponential?

On remembering how to solve... I guess it just depends on what other courses you're taking (if they use them at all). I've certainly forgotten how to do those infinite sums for solving DE's for example.

 

[K.I.L.E.R]

ILATE

Inverse.
Log.
Arithmatic.
Trig.
Exponent.

Ah, so you've gotten to the "guessing" of solutions with sine/cosine/exponential?

On remembering how to solve... I guess it just depends on what other courses you're taking (if they use them at all). I've certainly forgotten how to do those infinite sums for solving DE's for example.

 

[AlNom]

Gotta love exponentials