AC Lim's answer to NT's Secondary 2 Maths Singapore question.
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Hope this helps
Date Posted:
2 months ago
how did u get -2xy?
x² + y² = (x+y)² - 2xy
Cause when you expand
(x+y)² = [x²+y² +2xy]
Therefore, to get x²+y² you need to minus 2xy.
In the end,
x²+y² = [x²+y²+2xy] -2xy = x²+y²
Cause when you expand
(x+y)² = [x²+y² +2xy]
Therefore, to get x²+y² you need to minus 2xy.
In the end,
x²+y² = [x²+y²+2xy] -2xy = x²+y²
thank u so much
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