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6nn8602 幼苗
共回答了12个问题采纳率:83.3% 举报
(1)−22÷(−
1
5)2×|−5|×(−0.1)3
=-4×25×5×(-0.001)
=500×0.001
=0.5;
(2)(−
1
2−
1
3+
1
4)×(−12)
=(-[1/2])×(-12)-[1/3]×(-12)+[1/4]×(-12)
=6+4-3
=10-3
=7;
(3)(8xy-x2+y2)-4(x2-y2+2xy-3)
=8xy-x2+y2-4x2+4y2-8xy+12
=(-1-4)x2+(1+4)y2+(8-8)xy+12
=-5x2+5y2+12;
(4)(3x2y+5xy2)-9x2y-(6x2y+2xy2-12x2y)
=3x2y+5xy2-9x2y-6x2y-2xy2+12x2y
=(5-2)xy2+(3-9-6+12)x2y
=3xy2.
点评:
本题考点: 整式的加减;有理数的混合运算.
考点点评: 本题考查了有理数的混合运算与整式的加减运算,熟记合并同类项法则是解题的关键,去括号时要注意符号的改变.
1年前
你能帮帮他们吗