SOLUTION: 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

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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
I am so confused right now, I don't know what to do. It's been years since I had Algebra.



Found 3 solutions by shree840, mananth, Alan3354:
Answer by shree840(260) About Me  (Show Source):
You can put this solution on YOUR website!
(s+t)(s-t)(s+t)(s-t) we will use formula s^2-t^2=(s+t)(s-t)
(s^2-t^2)(s^2-t^2)
s^4-2s^2y^2+t^4 ANS
how did you get T^2 when you multiply the t's

Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
In identities there is a formula for the product of sum and difference of two variables.
(a+b)(a-b)=a^2-b^2
(s+t)(s-t)(s+t)(s-t)
%28s%5E2-t%5E2%29%28s%2Bt%29%28s-t%29
%28s%5E2-t%5E2%29%28s%5E2-t%5E2%29
%28s%5E2-t%5E2%29%5E2
Another formula is (a-b)^2= a^2-2ab+b^2
here a= s^2 & b=t^2
s%5E4-2s%5E2t%5E2%2Bt%5E4

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
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"