题目内容
计算:
(1)(-7)+(+25)-(-15);
(2)(3a-2)-3(a-5);
(3)3x2-3x2-y2+5y+x2-5y+y2
(4)(4a2b-5ab2)-(3a2b-4ab2)
(1)(-7)+(+25)-(-15);
(2)(3a-2)-3(a-5);
(3)3x2-3x2-y2+5y+x2-5y+y2
(4)(4a2b-5ab2)-(3a2b-4ab2)
分析:根据有理数的加减、去括号及合并同类项的法则,进行运算即可.
解答:解:(1)原式=25+15-7
=33;
(2)原式=3a-2-3a+15
=13;
(3)原式=x2;
(4)原式=4a2b-5ab2-3a2b+4ab2
=a2b-ab2.
=33;
(2)原式=3a-2-3a+15
=13;
(3)原式=x2;
(4)原式=4a2b-5ab2-3a2b+4ab2
=a2b-ab2.
点评:本题考查了整式的加减,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.
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