下列城市属于贵州省且有“江南煤海”之称的是( )
A:遵义
B:六盘水
C:贵阳
D:铜仁
Are you able to send a letter with pictures and sounds to someone somewhere in the world without a stamp(邮票) on it? Using a computer you can send e-mails quickly and easily. The post is much slower than e-mail. E-mail can send its message to the other side of the world in seconds.
E-mail is easy to use and it saves time and money. The differences in time in different parts of the world do not matter when sending e-mail. It's twenty-four-hour service(服务) that you can send e-mail at any time of the day or night. No one has to be there to get e-mail. It does not matter if your friends are in beds when you send e-mail to them, or you are seeing a movie at the movie theater when they send e-mail back.
食物中所含的六大营养物质中,能为人体提供能量的是()
(Ⅰ)求函数f(x)的解析式;
(Ⅱ)若f(m2+2m)+f(m)>0,求m的取值范围.
x
1
2
3
4
y
12
28
42
56
(Ⅰ)在图中画出表中数据的散点图;
(Ⅱ)根据(Ⅰ)中的散点图拟合y与x的回归模型,并用相关系数加以说明;
(Ⅲ)建立y关于x的回归方程,预测第5年的销售量约为多少?.
附注:参考数据: ∑i=14(yi−y¯)2≈32.6 , 5≈2.24 , ∑i=14xiyi=418 .
参考公式:相关系数 r=∑i=1n(xi−x¯)(yi−y¯)∑i=1n(xi−x¯)2∑i=1n(yi−y¯)2 ,
回归方程 y^=a^+b^x 中斜率和截距的最小二乘法估计公式分别为: b^=∑i=1n(xi−x¯)(yi−y¯)∑i=1n(xi−x¯)2=∑i=1nxiyi−nx¯y¯∑i=1nxi2−nx¯2 , a^=y¯−b^x¯ .