《2025年初中必刷题七年级数学上册苏科版》

1[中]计算:
(1)$7\frac {1}{3}×(-5)+7×(-7\frac {1}{3})-12×7\frac {1}{3};$
(2)$(-5\frac {3}{5})×(-2)+(-5.6)×7-4×(-5\frac {3}{5}).$

答案： 【解】
(1)原式$=7\frac{1}{3}×[(-5)-7-12]=\frac{22}{3}×(-24)=-176.$
(2)原式$=(-5\frac{3}{5})×(-2+7-4)=(-5\frac{3}{5})×1=-5\frac{3}{5}.$

2[中]计算:
(1)$(-\frac {5}{8})×\frac {3}{14}×(-\frac {16}{5})×(-\frac {7}{6}).$
(2)$(-1.75)+(-\frac {1}{3})+\frac {4}{5}+1.05+(-\frac {2}{3})+2.2.$

答案： 【解】
(1)原式$=-(\frac{5}{8}×\frac{3}{14}×\frac{16}{5}×\frac{7}{6})=-(\frac{5}{8}×\frac{16}{5}×\frac{3}{14}×\frac{7}{6})=-[(\frac{5}{8}×\frac{16}{5})×(\frac{3}{14}×\frac{7}{6})]=-(2×\frac{1}{4})=-\frac{1}{2}.$
(2)原式$=[(-1.75)+1.05]+[(-\frac{1}{3})+(-\frac{2}{3})]+(\frac{4}{5}+2.2)=-0.7-1+3=1.3.$

3[2025江苏南京质检,中]计算:$(-51)+(+12)+(-7)+(-11)+(+36).$

答案： 【解】原式$=[(-51)+(-7)+(-11)]+(12+36)=[-(51+7+11)]+48=-69+48=-21.$

4[中]计算:$1+2-3-4+5+6-7-8+9+10-11-12+... +97+98-99-100.$

答案： 【解】$1+2-3-4=-4,5+6-7-8=-4,9+10-11-12=-4,\cdots,97+98-99-100=-4$,所以原式$=-4×25=-100.$

5[中]计算:$(-\frac {1}{2}×\frac {3}{2})×(-\frac {2}{3}×\frac {4}{3})×(-\frac {3}{4}×\frac {5}{4})×... ×(-\frac {2021}{2022}×\frac {2023}{2022}).$

答案： 【解】原式$=-\frac{1}{2}×(\frac{3}{2}×\frac{2}{3})×(\frac{4}{3}×\frac{3}{4})×(\frac{5}{4}×\frac{4}{5})×\cdots×(\frac{2021}{2020}×\frac{2020}{2021})×(\frac{2022}{2021}×\frac{2021}{2022})×\frac{2023}{2022}=-\frac{1}{2}×1×1×1×\cdots×1×1×\frac{2023}{2022}=-\frac{2023}{4044}.$

6计算:$(-\frac {1}{84})÷(\frac {1}{6}-\frac {5}{14}+\frac {1}{3}-\frac {3}{7}).$

答案： 【解】$(\frac{1}{6}-\frac{5}{14}+\frac{1}{3}-\frac{3}{7})÷(-\frac{1}{84})=(\frac{1}{6}-\frac{5}{14}+\frac{1}{3}-\frac{3}{7})×(-84)=-14+30-28+36=24$,所以原式$=\frac{1}{24}.$