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发表于 25-8-2012 11:08 AM
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Situation 1:
6 ÷ 2(a+b)
=6 ÷ 2 x (a+b)
=3 x (a+b)
=3a + 3b
6 ÷ [ 2(a+b) ]
= 6 ÷ [ 2a+2b ]
= 3 ÷ ( a+b )
PEMDAS,Parenthesis指的是先做"括号里"的运算;
Situation 2:
6 ÷ 2 × a
= 3 × a
= 3a
6 ÷ 2a
= 3 / a
若 2a,意思是2 is coefficient of a, a is an unknown.
所以 2a是当作一整体,即可当作 (2a), 2是系数。=> 6 ÷ (2a)
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