2026年精英新课堂七年级数学上册人教版第26页答案
1. 用简便方法计算:
(1)$5.5+(-1.1)+(-3.9)$;
(2)$-0.8-5.2+11.6-5.6$;
(3)$-165+265-78-22+65$;
(4)$11.125-1\frac{1}{4}+4\frac{7}{8}-4.75$;
(5)$3\frac{3}{7}-(2.4-1\frac{4}{7})+(-1.6)$;
(6)$(-7.3)-(-6\frac{5}{6})+\left|-3.3\right|+1\frac{1}{6}$;
(7)$6\frac{1}{4}-3.3-(-6)-(-3\frac{3}{4})+4+3.3$;
(8)$(-0.125+25\frac{3}{4})-\left|-8\frac{7}{8}\right|-25.75$;
(9)$\left|-7\frac{3}{8}+4\frac{1}{2}\right|-18\frac{1}{2}+\left|-6-\frac{1}{2}\right|+\frac{1}{8}$;
(10)$(-12\frac{1}{2})-[5\frac{1}{4}-(+3\frac{1}{7})+(-5\frac{1}{4})+(-2\frac{6}{7})]$。

答案

1. (1) 原式$=5.5+[(-1.1)+(-3.9)]=5.5-5=0.5.$
(2) 原式$=(-0.8-5.2)+(11.6-5.6)=-6+6=0.$
(3) 原式$=(-165+265)-(78+22)+65=100-100+65=65.$
(4) 原式$=11 \frac{1}{8}-1 \frac{1}{4}+4 \frac{7}{8}-4 \frac{3}{4}=(11 \frac{1}{8}+4 \frac{7}{8})-(1 \frac{1}{4}+4 \frac{3}{4})=16-6=10.$
(5) 原式$=3 \frac{3}{7}-2.4+1 \frac{4}{7}-1.6=(3 \frac{3}{7}+1 \frac{4}{7})+(-2.4-1.6)=5-4=1.$
(6) 原式$=(-7.3+3.3)+(6 \frac{5}{6}+1 \frac{1}{6})=-4+8=4.$
(7) 原式$=6 \frac{1}{4}-3.3+6+3 \frac{3}{4}+4+3.3=(6 \frac{1}{4}+3 \frac{3}{4})+(-3.3+3.3)+(6+4)=10+0+10=20.$
(8) 原式$=-\frac{1}{8}+25 \frac{3}{4}-8 \frac{7}{8}-25 \frac{3}{4}=(-\frac{1}{8}-8 \frac{7}{8})+(25 \frac{3}{4}-25 \frac{3}{4})=-9.$
(9) 原式$=7 \frac{3}{8}-4 \frac{1}{2}-18 \frac{1}{2}+6 \frac{1}{2}+\frac{1}{8}=(7 \frac{3}{8}+\frac{1}{8})+(-4 \frac{1}{2}-18 \frac{1}{2}+6 \frac{1}{2})=7 \frac{1}{2}+(-16 \frac{1}{2})=-9.$
(10) 原式$=-12 \frac{1}{2}-5 \frac{1}{4}+3 \frac{1}{7}+5 \frac{1}{4}+2 \frac{6}{7}=-12 \frac{1}{2}+(3 \frac{1}{7}+2 \frac{6}{7})+(-5 \frac{1}{4}+5 \frac{1}{4})=-12 \frac{1}{2}+6+0=-6 \frac{1}{2}.$