习题2.8第1题答案
(1)8-(-4)÷22×3
=8-(-4)÷4×3
=8-(-1)×3=8-(-3)
=8+3
=11
(2)(-3)3÷(-3)÷9
=(-27)×(-1/3)×(1/9)
=1
(3)7×32÷3+(-3)2
=7×9×1/3+9
=21+9
=30
(4)-5+(-2)4-24÷(-2)3
=-5+16-16÷(-8)
=11-(-2)
=13
习题2.8第2题答案
(1)(-28)÷(-6+4)+(-1)×5
=(-28)÷(-2)+(-5)
=14+(-5)
=9
(2)2÷(-2)+0÷7-(-8)×(-2)
=-1+0-16
=-17
(3)3×42+80÷5÷23-27=3×16+16÷8-27
=48+2-27
=23
(4)122÷(-3)2×(-2)3-(-9)2÷33
=144×1/9×(-8)-81×1/27
=16×(-8)-3
=-131
习题2.8第3题答案
(1)(2/3+1/2)÷(-1/12)×(-12)
=(2/3+1/2)×(-12)×(-12)
=2/3×144+1/2×144
=96+72
=168
(2)(-6)2÷(-1/2+1/4+1/2)
=36×4
=144
(3)(1/3+1/2-5/6-3/4)÷(-1/3)2
=(1/3+1/2-5/6-3/4)÷1/9
=1/3×9+1/2×9-5/6×9-3/4×9
=-27/4
(4)(-2)3×8-8×(1/2)3+8÷1/8
=(-8)×8-8×1/8+8×8
=-64-1+64
=-1
习题2.8第4题答案
(1)191
(2)-50
(3)0.79992
(4)-998.56