七上数学有理数加、减、乘、除、乘方运算 (1)(−48)÷8+(−25)×(−2)−4 解:=−6+50−4 =−6−4+50 =−10+50 =40 (2)(−2)2×5−(−2)3+4+(−1)100×5 解:=4×5+8+4+5 =20+8+4+5 =37 (3)−7×−5−90÷−15 解:原式=35−−6 =35+6 =41 (5)13−20−(−18)+(−1) 解:原式=13−20+18−1 =31−21 =10 (6)−110×2+−23÷4 解:原式=1×2+−8÷4 =2+−2 =0 (7)−14×−3−4−−23÷6 解:=−1×−3−4−−8÷6 =3−12÷6 =1 (8)+4−−7+−8 解: =+4++7+−8 =+11+−8 =3 (9)−8.9−−4.7+7.5 解:=−8.9+4.7+7.5 =−8.9++12.2 =3.3 (10)−20+(+3)−(−5)−7 解:=−20+3+5−7 =−19 (11)23+−17+6+−22 解:=23−17+6−22 =23+6+−17−22 =29−39 =−10 (12)−5−+6+−2−−9
