4/7.31+6/7.41+9/10.41+7/10.57 em cần chi tiết

2 bình luận về “4/7.31+6/7.41+9/10.41+7/10.57 em cần chi tiết”

1. 4/(7.31)+6/(7.41)+9/(10.41)+7/(10.57)

   =20/(31.35)+30/(35.41)+45/(41.50)+35/(50.57)

   =5.(4/(31.35)+6/(35.41)+9/(41.50)+7/(50.57))

   =5.(1/31-1/35+1/35-1/41+1/41-1/50+1/50-1/57)

   =5.(1/31-1/57)

   =5.(57-31)/1767

   =5.26/1767

   =130/1767

   #Darmon

   Trả lời
2. Đặt A =4/(7 * 31) + 6/(7 * 41) + 9/(10 * 41) + 7/(10 * 57)

   1/5 A = 4/(31 * 35) + 6/(35*41) + 9/(41 *50) + 7/(50 * 57)

   1/5 A = 1/31 – 1/35 + 1/35 – 1/41 + 1/41 – 1/50 + 1/50 – 1/57

   1/5 A = 1/31 + (-1/35 + 1/35 ) + (-1/41 +1/41) + (-1/50 + 1/50) – 1/57

   1/5 A = 1/31 – 1/57

   A = (1/31 – 1/57)*5

   A = 26/1767 *5

   A = 130/1767

   Trả lời