问题
解答题
计算: (1)18-(-24)÷(-4); (2)(-2)2-|-7|+3-2×(-
(3)-1-「-1+(1-0.5×23)」; (4)-3xy-(2xy-5xy); (5)3(5a+4)-(3a-10); (6)先化简,再求值:(6a2+4ab)-2(3a2+ab-
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答案
(1)原式=18-6=12;
(2)原式=4-7+3+1=1;
(3)原式=-1-[-1+1-4]=-1+4=3;
(4)原式=-3xy-2xy+5xy=0;
(5)原式=15a+12-3a+10=12a+22;
(6)原式=6a2+4ab-6a2-2ab+b2=2ab+b2,
当a=2,b=1时,原式=2×2×1+1=5.