会计考友 发表于 2012-8-15 12:55:17

新GRE数学要点:Distributive Law

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:
  3*(2x+y)=3*2x+3*y
  3a*(2x+y)=3a*2x+3a*y,
  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.
  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.
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