问题标题:
初中数学疑难.谢谢帮助!1.已知x/y=4/3,求3x²-5xy+2y²/2x²+3xy-5y²的值.
更新时间:2024-05-08 09:42:36
问题描述:

初中数学疑难.谢谢帮助!

1.已知x/y=4/3,求3x²-5xy+2y²/2x²+3xy-5y²的值.

金花回答:
  (3x²-5xy+2y²)/(2x²+3xy-5y²)   =【(3x²-5xy+2y²)×(1/y²)】/【(2x²+3xy-5y²)×(1/y²)】   =【(3x²)×(1/y²)-(5xy)×(1/y²)+(2y²)×(1/y²)】/【(2x²)×(1/y²)+(3xy)×(1/y²)-(5y²)×(1/y²)】   =【3(x/y)²-5(x/y)+2】/【2(x/y)²+3(x/y)-5】   =【3×(4/3)²-5×(4/3)+2】/【2×(4/3)²+3×(4/3)-5】   =6/23
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