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苏科版七年级上册数学书习题2.8答案

时间:2016-04-29 来源:书通网 共计4题

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

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