Tính bằng cách hợp lí: a)`(2004xx2005+2006xx6-6)/(2005xx1997+4xx2005)` b)`(1999xx2000+2001xx5-5)/(504xx2000+500xx2000)`

1 bình luận về “Tính bằng cách hợp lí: a)`(2004xx2005+2006xx6-6)/(2005xx1997+4xx2005)` b)`(1999xx2000+2001xx5-5)/(504xx2000+500xx2000)`”

1. a)(2004xx2005+2006xx6-6)/(2005xx1997+4xx2005)

   =(2004×2005+(2005+1)×6-6)/(2005×(1997+4))

   =(2004×2005+2005×6+6-6)/(2005×2001)

   =(2005×(2004+6))/(2005×2001)

   =(2005×2010)/(2005×2001)

   =2010/2001=(670.3)/(667.3)=670/667

   b)(1999xx2000+2001xx5-5)/(504xx2000+500xx2000)

   =(1999×2000+(2000+1)×5-5)/((504+500)×2000)

   =(1999×2000+2000×5+5-5)/(1004×2000)

   =(2000×(1999+5))/(1004×2000)

   =(2000×2004)/(1004×200)

   =2004/1004=(501.4)/(251.4)=501/251

    

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