how to expand:
a. (y＋1╱y)(y－1/y)
b.(y＋1/y)²
By using the result of (a) and (b) or otherwise，expand (y＋1╱y)(y－1/y)－(y＋1/y)²
Thankyou!
MATH Question?
2016-01-18 11:17 am
回答 (1)
2016-01-18 12:37 pm
✔ 最佳答案
a. (y＋1/y)(y－1/y) =y^2－1/y^2
b.(y＋1/y)^2
=y^2+1/y^2+2
By using the result of (a) and (b) or otherwise，expand (y＋1/y)(y－1/y)－(y＋1/y)^2
(y＋1/y)(y－1/y)－(y＋1/y)^2
=(y^2－1/y^2)－(y^2+1/y^2+2)
=－2/y^2－2
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