用2种方法计算:(n+5)^2-(n-5)^2

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用2种方法计算:(n+5)^2-(n-5)^2
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用2种方法计算:(n+5)^2-(n-5)^2
用2种方法计算:(n+5)^2-(n-5)^2

用2种方法计算:(n+5)^2-(n-5)^2
:(n+5)^2-(n-5)^2
=(n+5+n-5)(n+5-n+5)
=2n*10
=20n;
:(n+5)^2-(n-5)^2
=n²+25+10n-n²-25+10n
=20n;