Question 430834
I'm trying to help my niece with an algebra problem that has both of us stumped... 
(s+t)(s-t)(s+t)(s-t) 
The answer provided in her book is: 
s^4-2t^2s^2t^2 
I can't even get close to this answer. I got the s^4 and think I got the s^2 and t^2, but I can't figure out the -2t^2. 
If you can tell me what I'm doing wrong, I'd appreciate it. 
I came up with: 
(s)(s)(s)(s) = s^4 
(t)(-t)(t)(-t) = t^2 ***** No, that's t^4, take another look.
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s^4-2t^2s^2t^2 *** Either the book is wrong, or you copied it wrong.
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The other tutors give the right answer.
One has a typo, and entered a "y" instead of a "t"