What am I missing here?

• Mar 18th 2007, 02:55 PM
ahroogahh
What am I missing here?
Hi all, this is really bothering me... I am just not seeing how ...

(x-a)+(x-a)(x+a) ----> (x-a)(x+a+a)

..... I know this is true because I have looked it up in a solution manual and my professor did this on the board. How!!!? Any help would be greatly apprieciated!

• Mar 18th 2007, 03:31 PM
ThePerfectHacker
Quote:

Originally Posted by ahroogahh
Hi all, this is really bothering me... I am just not seeing how ...

(x-a)+(x-a)(x+a) ----> (x-a)(x+a+a)

..... I know this is true because I have looked it up in a solution manual and my professor did this on the board. How!!!? Any help would be greatly apprieciated!

I think you want to say,
(x-a)(x+a+1)

Because you have,
(x-a)(1)+(x-a)(x+a)

Notice you have a common factor, (x-a), thus,

(x-a)(1+x+a)
• Mar 18th 2007, 03:38 PM
Jhevon
Quote:

Originally Posted by ahroogahh
Hi all, this is really bothering me... I am just not seeing how ...

(x-a)+(x-a)(x+a) ----> (x-a)(x+a+a)

..... I know this is true because I have looked it up in a solution manual and my professor did this on the board. How!!!? Any help would be greatly apprieciated!

(x-a)+(x-a)(x+a) ----> (x-a)(x+a+a) . this is not always true, are you sure it's not a typo? put a = 3 for example and expand the left hand side, you get a different answer from when you expand the right hand side with a = 3.

the way i see to do this is to factor the common (x - a) out

(x-a)+(x-a)(x+a) = (x - a)(1 + (x + a)) = (x - a)(x + a + 1)
• Mar 18th 2007, 03:57 PM
ahroogahh
Thanks to both of you... I did typo the equation. one of the 'a' terms should have been '+1' as you both pointed out. Thanks for answering my question typo's and all.