《2025年实验班提优训练七年级数学上册人教版》

1. (2025·福建莆田期中)计算：
(1)$2.7-8.5-3.5+1.3$；
(2)$(+\frac {1}{5})-(+\frac {1}{4})+(-\frac {3}{5})-(-6\frac {3}{4})$；
(3)$4\frac {3}{4}-(+3.85)-(-3\frac {1}{4})+(-3.15)$.

答案： 1.
(1)2.7-8.5-3.5+1.3
=2.7+(-8.5)+(-3.5)+1.3
=(2.7+1.3)+[(-8.5)+(-3.5)]
=4+(-12)=-8.
(2)$(+\frac {1}{5})-(+\frac {1}{4})+(-\frac {3}{5})-(-6\frac {3}{4})$
$=(+\frac {1}{5})+(-\frac {1}{4})+(-\frac {3}{5})+6\frac {3}{4}$
$=[(+\frac {1}{5})+(-\frac {3}{5})]+[(-\frac {1}{4})+6\frac {3}{4}]$
$=-\frac {2}{5}+6\frac {1}{2}=-\frac {4}{10}+6\frac {5}{10}=6\frac {1}{10}.$
(3)$4\frac {3}{4}-(+3.85)-(-3\frac {1}{4})+(-3.15)$
$=4\frac {3}{4}+(-3.85)+3\frac {1}{4}+(-3.15)$
$=(4\frac {3}{4}+3\frac {1}{4})+[(-3.85)+(-3.15)]$
$=8+(-7)=1.$

2. (2025·上海嘉定区期末)计算：$-16×(-3\frac {1}{7})-(-9)×3\frac {1}{7}+11×(-3\frac {1}{7})$.

答案： 2.原式$=16×3\frac {1}{7}+9×3\frac {1}{7}-11×3\frac {1}{7}$
$=(16+9-11)×3\frac {1}{7}=14×\frac {22}{7}=44.$

3. (2025·天津和平区期末)计算：$(-5)×(-\frac {11}{5})-11×\frac {11}{5}-3×(-\frac {22}{5})$

答案： 3.原式$=\frac {11}{5}×5-\frac {11}{5}×11+\frac {11}{5}×6$
$=\frac {11}{5}×(5-11+6)=0.$

4. (2025·上海松江期末)计算：$5×\frac {6}{5}+6×(-\frac {6}{5})-3×(-1.2)$.

答案： 4.原式$=5×\frac {6}{5}-6×\frac {6}{5}+3×\frac {6}{5}$
$=\frac {6}{5}×(5-6+3)=\frac {6}{5}×2=\frac {12}{5}.$