问题
解答题
先化简，再求值：[（a-2b）2+（a+4b）（3a-b）]÷（2a），其中a是27的立方根，b是4的算术平方根．
答案
原式=（a2-4ab+4b2+3a2-ab+12ab-4b2）÷（2a）
=（4a2+7ab）÷（2a）
=2a+
b，7 2
当a=
=3，b=3 27
=2时，原式=2×3+4
×2=13．7 2
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先化简，再求值：[（a-2b）2+（a+4b）（3a-b）]÷（2a），其中a是27的立方根，b是4的算术平方根．
原式=（a2-4ab+4b2+3a2-ab+12ab-4b2）÷（2a）
=（4a2+7ab）÷（2a）
=2a+
b，7 2
当a=
=3，b=3 27
=2时，原式=2×3+4
×2=13．7 2
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| Peter and Paul passed by a small house on their way home late at night. They saw thick 1 coming out of its windows. "It's on fire!" said Peter. "We must get help." The two brothers ran 2 the road shouting "Fire! Fire!" They 3 on the door of the next house. They asked them to 4 the police and the firemen. They ran back to the house. They saw 5 the window an old lady sitting in an arm-chair. It was 6 that she could not move. Peter and Paul tried hard to carry her out of the 7 and so they did! Some neighbours (邻居) came and helped take some things out. In no time the firemen 8 as well as the policemen. The fire was put out. The old lady cried sadly 9 she was not hurt. She thanked Peter and Paul and her neighbours 10 . | ||||
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