如图,某校七年级三个班学生开展校内种植活动,计划在校内建造一个矩形菜地,为充分利用现有资源,该矩形菜地一面靠墙(墙的长度为
),另外三面用栅栏围成,中间再用栅栏把它分成三个面积相等的矩形,已知栅栏的总长度为
,设较小矩形的宽为
.
(1)若矩形菜地的总面积为
,求
的值;
(2)当
为何值时,矩形菜地的总面积最大?最大面积为多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3b749f9acb5f0de709a1709bbdd42614.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f03c367201c385fcf9bdbf09d22b9e9d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/cc3bde6ef2ee5b749b4d48d706543cdb.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2024/3/31/45b8163d-24b2-492d-a498-a3f369332105.png?resizew=164)
(1)若矩形菜地的总面积为
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a2ff3b4e327d32d7505fbb40d47669.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
更新时间:2024-03-31 10:17:16
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适中
(0.65)
【推荐1】有一块长为
米,宽为
米的长方形场地,计划在该场地上修建宽均为x米的两条互相垂直的道路,余下的四块长方形场地建成草坪.
,
,且四块草坪的面积和为
平方米,则每条道路的宽
为多少米?
(2)若
,
,且四块草坪的面积和为
平方米,则原来矩形场地的长和宽各为多少米?
(3)已知
,
,现要在场地上修建若干条宽均为
米的纵横小路,假设有
条水平方向的小路,
条竖直方向的小路(其中
n为常数),使草坪地的总面积为
平方米,则
(直接写出答案).
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0a6936d370d6a238a608ca56f87198de.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2c94bb12cee76221e13f9ef955b0aab1.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e48692e011dd9292bbf4b17057464461.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0db91eb602cbc56219336af1ee36f529.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69b7c046c15d4a78600ef3eb4dcb292a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d2b2e94ba5f9efe0b8c819918d337f87.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/707ea658f3a9359f5740d5aab48f7948.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/69b7c046c15d4a78600ef3eb4dcb292a.png)
(3)已知
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7fa0cb2ff4549787d8bcd3be27ea5c85.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f704179f68ce7fb0ccea3d5e36282ffd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61128ab996360a038e6e64d82fcba004.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6a24198bd04c29321ae5dc5a28fe421.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c2d05f222821f941f361aeb5d5ff26ba.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/13f10e5b0ca88f6dddf0f406bed99aff.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/74d48413457e48bfc45ee289139fd706.png)
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【推荐2】教育部联合共青团中央、全国少工委印发《关于加强中小学劳动教育的意见》.为了更好的落实文件精神,丰台区某校八年级学生到北京农机试验站学农教育基地进行了为期一周的学农活动.在基地,学生们进行了翻地整地、菜苗移植、认识蔬菜、制作香皂等活动.在参观牛舍的过程中,同学们发现工作人员为了保护小牛,给每头小牛盖了专门的牛舍.如图所示,整个小牛舍区域是长20 m,宽6 m的矩形,其中每一个小牛舍是一面靠墙,其余三面用围栏围成的矩形.为了照顾小牛方便,工作人员在每个小牛舍周围留着等宽的小路,如果每个小牛舍的面积是12.5 m2,请求出小路的宽.(设小路的宽为x m)
![](https://img.xkw.com/dksih/QBM/2020/8/12/2526396491866112/2526470483812352/STEM/51cdbf7cc49d4586b7d71d8d2ea171aa.png?resizew=371)
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解答题-证明题
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【推荐1】如图,正方形
两条对角线
、
交于
,过
任作一直线
与边
,
交于
,
,
的垂直平分线与边
,
交于
,
.设正方形
的面积为
,四边形
的面积为
.
![](https://img.xkw.com/dksih/QBM/2020/4/9/2437943507877888/2439004123160576/STEM/f3d3fa3806c341e6a1fa012c509b9693.png?resizew=153)
(1)求证:四边形
是正方形;
(2)若
,求
的取值范围.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/60ef95894ceebaf236170e8832dcf7e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d40b319212a7e7528b053e1c7097e966.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1dde8112e8eb968fd042418dd632759e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0c88d9142df6ba8e43c1a93bd04a1362.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d78abbad68bbbf12af10cd40ef4c353.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ac047e91852b91af639feec23a9598b2.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/54a5d7d3b6b63fe5c24c3907b7a8eaa3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411461db15ee8086332c531e086c40c7.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/411b38a18046fea8e9fab1f9f9b80a5f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e097c8d4c948de063796bd19f85b3a9a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96198405db093eb43952282a69332f92.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
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(1)求证:四边形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/96198405db093eb43952282a69332f92.png)
(2)若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f9c752ebe8516e7d3327f3410473d9a6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1e0bd63f55069a3bc870915010b39225.png)
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【推荐2】已知二次函数图像的对称轴为直线
,且过点
与
,请你判断下列四个说法是否正确,并说明理由.
①当
时,函数有最大值2;
②当
时,函数有最小值
;
③点P是第一象限内抛物线上的一个动点,则
面积的最大值为
;
④对于非零实数m,当
时,y都随着x的增大而减小.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b384412acba251d87902ab928902f16.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6f2b1f4120365cb6ee4925fe417563f9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8c3aa54a79b21b2f5be603e8a83017f9.png)
①当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61ca447a80ebb3b46fc2d9f5c3f20f60.png)
②当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/61ca447a80ebb3b46fc2d9f5c3f20f60.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/274a9dc37509f01c2606fb3086a46f4f.png)
③点P是第一象限内抛物线上的一个动点,则
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/53502463cc76201000e02df314e58769.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a4b8503f4706b8321e4e79a87eadea84.png)
④对于非零实数m,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/be70babbf68dfdfd676e268473d7dc98.png)
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