新GRE数学要点:Distributive Law

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Distributive Law 　　Like real number, when multiplying a sum or difference of terms, the distributive property of multiplication allows us to distribute the multiplying term among the terms being added or subtracted.
　　Example:
$ E7 I1 K: ]2 r; C3 Y4 {　　3*(2x+y)=3*2x+3*y
' L# _" u+ i4 x6 l　　3a*(2x+y)=3a*2x+3a*y,
7 ?- J4 T$ H! L. d( ~9 H　　3x*(2x+y)=3x*2x+3x*y.
　　(3x+4)*(2x+y)=(3x+4)*2x+(3x+4)*y=3x*2x+4*2x+3x*y+4*y.
　　Remember:
　　Do not forget to multiply all the terms inside the parenthesis.
: |- X4 e8 C3 }　　For division, the sum and difference in the numerator can be distributed:(x+y)/(2x+y)=x/(2x+y)+y/(2x+y).
　　For division, the sum and difference in the denominator cannot be distributed :(x+y)/(2x+y)≠(x+y)/2x+(x+y)/y.