试题

题目:
计算:
(1)(-7)+(+10)+(-1)+(-2)
(2)-22×5-(-3)×(-5)÷(-
1
5

(3)4x2y-9xy2+7-4x2y+10xy2-4
(4)3(2x2-xy)-4(x2-xy+3)
答案
解:(1)(-7)+(+10)+(-1)+(-2),
=-7+10-1-2,
=0.

(2)-22×5-(-3)×(-5)÷(-
1
5
),
=-20-15÷(-
1
5
),
=-20+75,
=55.

(3)4x2y-9xy2+7-4x2y+10xy2-4,
=(4x2y-4x2y)+(-9xy2+10xy2)+7-4,
=xy2+3;

(4)3(2x2-xy)-4(x2-xy+3),
=6x2-3xy-4x2+4xy-12,
=2x2+xy-12.
解:(1)(-7)+(+10)+(-1)+(-2),
=-7+10-1-2,
=0.

(2)-22×5-(-3)×(-5)÷(-
1
5
),
=-20-15÷(-
1
5
),
=-20+75,
=55.

(3)4x2y-9xy2+7-4x2y+10xy2-4,
=(4x2y-4x2y)+(-9xy2+10xy2)+7-4,
=xy2+3;

(4)3(2x2-xy)-4(x2-xy+3),
=6x2-3xy-4x2+4xy-12,
=2x2+xy-12.
考点梳理
整式的加减;有理数的混合运算.
(1)直接进行有理数的加减运算即可.
(2)先进行幂的运算,然后再进行有理数的乘除运算即可.
(3)直接合并同类项即可得出答案.
(4)先去括号,然后合并同类项即可.
本题考查有理数的混合运算及整式的加减,解决此类题目的关键是熟记去括号法则,熟练运用合并同类项的法则,这是各地中考的常考点
计算题.
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