九年级寒假作业答案2017[1]
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九年级寒假作业答案2017[1]初中三年级
一.帮你学习 (1)-1 (2)B 二.双基导航 1-5 CCDAB (6)1;-6;7 (7)k≤2 (8)①③ (9)3/4 (10) (11)解:设应降价x元. (40-x)(20+2x)=1200 解得x1=10(舍去) x2=20 ∵为了尽快减少库存 ∴答:每件衬衫应降价20元. (12)解:①∵方程有两个不相等的实数根 ∴b2-4ac>0 ∴(-3)2-4(m-1)>0 ∴m<13/4 ②∵方程有两个相等的实数根时 b2-4ac=0 ∴(-3)2-4(m-1)=0 ∴m=13/4 ∴一元二次方程为x2-3x+9/4=0 ∴方程的根为x=3/2 (13)解:①10次:P=6/10=3/5; 20次:P=10/20=1/2; 30次:P=17/30; 40次:P=23/40 ②:P=1/2 ③不一定 (14)解:设 x2+2x=y ∴y2-7y-8=0 ∴y1=8 y2=-1 ∴当y=8时,由x2+2x=8得x1=2 x2=-4 当y=-1时,由x2+2x=-1得x=-1 (15)① 2x2+4x+3>0 2(x2+2x)>-3 2(x2+2x+1)>-3+2 2(x+1)2>-1 (x+1)2>-1/2 ∵(x+1)2≥0 ∴无论x为任意实数,总有2x2+4x+3>0 ②3x2-5x-1>2x2-4x-7 3x2-2x2-5x+4x-1+7>0 x2-x+6>0 x2-x>-6 (x-1/2)2>-23/4 ∵(x-1/2)2≥0 ∴无论x为任意实数,总有3x2-5x-1>2x2-4x-7 (16) (6,4) 三.知识拓展 1-4 CCDA (5)6或12 (6)1:1 (8)①PA=1/6 PB=2/6=1/3 PC=2/6=1/3 PD=1/6 ②不公平,因为棋子移动到每个点的概率不同 若想尽可能获胜,应选B点或C点 ③PA=8/36=2/9 (9)①如果一个四边形的对角线相互垂直,那么这个四边形的面积等于对角线乘积的一半 2017年9年级寒假作业答案——英语 听力部分 A,听对话,选答案. 听下面对话,回答第1题. M: What's the matter, Lucy Why did you call me W: Look at the washing machine! It's broken. I must get it repaired. Question: Why did the woman call the man 听下面对话,回答第2题. M: It's so hot today. Let's go swimming, OK W: I prefer to go to the supermarket. It's cool there, too. Question: What does the woman want to do 听下面对话,回答第3题. W: I have some difficulty in listening. Could you give me some advice M: You can listen to some English programs on the radio. It'll be really helpful! Question: What does the man suggest to the woman 听下面对话,回答第4题. W: What about the concert M: I have never heard a better voice! You should have gone there. Question: What does the man think of the concert 听下面对话,回答第5题. M: Mom, I think I'm well enough to go back to school now. W: No, dear. You'd better stay at home for another day or two. Question: What's the matter with the boy B,听对话,选答案. 听下面一段对话,回答第6和第7两个小题. W: Good afternoon, Sir. M: Good afternoon. Is there a table for two W: Sure.初中三年级