(1)-12+15-|-7-8|(2)(-3)×(-9)-(-5)(3)23-17-(-7)+(-16)(4)36×(19-16-118)(5)-13-(1-0.5)×13×[2-(-3)2](6)16÷(-2)3-(-18)×(-4)+(-1)100(7)化简求值5ab2+3a2b-3(a2b-23ab2),-数学

题文

(1)-12+15-|-7-8|
(2)(-3)×(-9)-(-5)
(3)23-17-(-7)+(-16)
(4)36×(
1
9
-
1
6
-
1
18
)
(5)-13-(1-0.5)×
1
3
×[2-(-3)2]
(6)16÷(-2)3-(-
1
8
)×(-4)+(-1)100
(7)化简求值5ab2+3a2b-3(a2b-
2
3
ab2),其中a=2,b=-1
(8)化简求值2(x2y+xy2)-2(x2y-1)-3xy2-2,其中x=-2,y=
1
2
题型:解答题  难度:中档

答案

(1)-12+15-|-7-8|
=-12+15-|-15|
=-12+15-15
=-12;
              
(2)(-3)×(-9)-(-5)
=27+5
=32;              

(3)23-17-(-7)+(-16)
=(23+7)+(-17-16)
=30+(-33)
=-3;                  

(4)36×(
1
9
-
1
6
-
1
18
)
=36×
1
9
-36×
1
6
-36×
1
8

=4-6-2
=-4;                

(5))-13-(1-0.5)×
1
3
×[2-(-3)2]
=-1-
1
2
×
1
3
×(2-9)
=-1-
1
2
×
1
3
×(-7)
=
1
6
;                   

(6)16÷(-2)3-(-
1
8
)×(-4)+(-1)100
=16÷(-8)-
1
2
+1
=-2-
1
2
+1
=-2+(-
1
2
)+1
=-
3
2
;          

(7)5ab2+3a2b-3a2b+2ab2
=5ab2++2ab2+3a2b-3a2b
=7ab2
当a=2,b=-1时,
原式=7×2×(-1)2=14;

(8)2x2
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