合理、灵活地计算 ①4/5×3.5+5.5×80%+0.8 ②(7/17×19-7/17)×17/18 ③15/6÷[6/11×(5/9-1/4)] ④2.35÷[4.75-4.5×(0.2+1/3)].
问题描述:
合理、灵活地计算
①
×3.5+5.5×80%+0.8 4 5
②(
×19-7 17
)×7 17
17 18
③1
÷[5 6
×(6 11
-5 9
)]1 4
④2.35÷[4.75-4.5×(0.2+
)]. 1 3
答
①
×3.5+5.5×80%+0.8,4 5
=0.8×3.5+5.5×0.8+0.8,
=(3.5+5.5+1)×0.8,
=10×0.8,
=8;
②(
×19-7 17
)×7 17
,17 18
=[(19-1)×
]×7 17
,17 18
=18×
×7 17
,17 18
=7;
③1
÷[5 6
×(6 11
-5 9
)],1 4
=
÷[11 6
×6 11
],11 36
=
÷11 6
,1 6
=
×6,11 6
=11;
④2.35÷[4.75-4.5×(0.2+
)],1 3
=2.35÷[4.75-4.5×(
+1 5
)],1 3
=2.35÷[4.75-4.5×
],8 15
=2.35÷[4.75-2.4],
=2.35÷2.35,
=1.