Sorry for the newbie question but I forgot some stuff. I punched in (x-3)^2 to my graphing calc and I got x^2+6x+9 as an anwser. Where''d the 6x come from, I remember something like this but it slipped my mind. Could someone explain this to me? Thx

(x-3)^2 = (x-3)(x-3)

Then if you remember the First, Outside, Inside, Last (FOIL):
(x-3)(x-3) = (x*x) + (x * -3) + (-3 * x) + (-3 * -3)
= x^2 + -3x + -3x + 9
= x^2 - 6x + 9

At least that''s what I got. So either I made a mistake or you copied one of your +/- signs wrong from your calculator.

Yah, I dont have calc with me, it must have been -6x. Thx, I remember now, don''t know how I didn''t think of that...

There is a distributive law that says a(b+c) = ab+ac. Just use that twice to derive the formula: (a-b)^2 = (a-b)(a-b) = (a-b)a+(a-b)(-b) = aa+(-b)a+a(-b)+(-b)(-b) = aa-ab-ab+bb = a^2-2ab+b^2.

i've just one question:

what mean (x-3)^3 ??

(x-3)*(x-3)*(x-3) ?

and what for (a+b)^c ?

I made a algebra solver years ago in turbo c++.... and I didn't the feature of this this kind of distributive law....

I'll fixe this problem.. and you'll can download my program to do algebra home work with my algebra solver


It can solve these problems:

-7ax^3y^5+a^2x^5y^3+4a^4x^4y^4-2a^3x^2y+7x^3y^5a+2a^3x^2y-a^2x^5y^3-4a^4x^4y^4
3x^3y^3z^3+7x^2y^2z^2-+15xyz+14-(-5xyz+-14x^2y^2z^2-5+9x^3y^3z^3)
(n^3-1)+(n^3+2n+1)+(-3n-1)+(2n^3+n)
((-8a^2+3a-5)+(5a^2+2a-2))-(2a^2+5a-8)
(-3xyz+4x^2+3y^3)-(2xyz-2xyz-4y^3)
((-8a^2+3a-5)+(5a^2+2a-2))-(2a^2+5a*-2xy^2)
-x(-3xyz+4x^2+3y^3)2-(2xyz-2xyz-4y^3)+3x^2(x+xy^2+4y^2)
2(4y^3x+2x^3y-(2xy*y^2)-((-2x^3y+2y^3x)+(x*3y*2x^2)))
(8-3x)(7x+5)-(x-3)(x+4)"; ¸
2a-(3b-4c)-(2a-(3b+4c))-(3b-(4c+2a))";
(3r^4s^4-(10r^2s^2-2r^4s^4+12r^2s^2))(r^2s^2-1)-(5r^2s^2+7r^4s^4)";
4(3b^2-5c^2)-(2(5b^2-3c^2)-3(-4b^2+c^2))
(2a+3c)(4a-5c)+(3a-c)(a+3c)-(a-2c)(5a+c)
(8.3r+3.2s+7.5)+(1.8r-s)+(5.7+2.3r-4.5s)

the goal was to can solve this problem:

5(2x+y) = 5z
10x+5y = 5z
10x-5z = -5y
-10x+5z = 5y
-2x+z = y



[edited by - fantasio on October 7, 2002 8:38:59 AM]

[edited by - fantasio on October 7, 2002 8:40:37 AM]

[edited by - fantasio on October 7, 2002 8:49:19 AM]

hehe...

(x-3)^10 = -30x^9+405x^8-3240x^7+17010x^6-x^4262440x^3+295245x^2-196830x+x^10+59049

I beleive this is the correct answer.

in a couple of millisecond.... so cool, but what''s the utility ??

If you''re interested to test or use this program (Algebra Solver) for your homework you can download tomorrow.

quote:Original post by perfectly_dark
Sorry for the newbie question but I forgot some stuff. I punched in (x-3)^2 to my graphing calc and I got x^2+6x+9 as an anwser. Where'd the 6x come from, I remember something like this but it slipped my mind. Could someone explain this to me?
Thx

(x+y)^2 is x^2 + 2*x*y + y^2

So (3+4)^2 is 3^2 + 2*3*4 + 4^2, 9+24+16 is 49, which is 7^2

So (x-3)^2 is x^2 -6*x + 9

Your calculator must be broken ...


[edited by - fidelio_ on October 7, 2002 6:31:27 PM]