【阅读理解】人教版七年级下册8.3 探究2:据统计资料,甲、乙两种作物的单位面积产值的比是
,现要把一块长
为
、宽
为
的长方形土地分为两块土地,分别种植这两种作物,怎么样划分这块土地,使甲、乙两种作物的总产量的比是
?
【解题过程】如图1,若甲、乙两种作物的种植区分别为长方形
和
,此时设
,
,根据题意,列出方程组:
,解得
.
过长方形土地的长边上离一端
处,作这条边的垂线,把这块土地分为两块长方形土地,较大一块土地种植甲作物,其面积为:
,
较小的一块土地种乙种作物,其面积为:
.
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/6/ed8bd427-d245-4c1d-bb89-02b14b8cfe4c.png?resizew=708)
(1)【尝试应用】同学们从以上解决方法得到启发提出解决上述问题的另一思路:
若按如图2所示,划分出一块三角形土地
种植乙种作物,其余土地种植甲种作物,则
应该取多长?
(2)【拓展应用】现要把另一块长
为
、宽
为
的长方形土地建成花园小广场,设计方案如图3所示,阴影区域为绿化区(四块绿化区为全等的直角三角形),空白区域为活动区,且四周出口宽度一样(
),设
.当出口宽为多少米时,活动区的面积最大?最大面积是多少?
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37d65e051e943ab28fa57aee2fb57994.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92f256afee1098dac22f423b19b43c89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f631cfdf4666db95beb923072ced8d95.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c60fe5130254a1d38bb4fd0015630f6d.png)
【解题过程】如图1,若甲、乙两种作物的种植区分别为长方形
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b80a0e428cb894bfd09a6129a73ea4ac.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9238757804254960bc40fa9d87065559.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c40a630abdfd2a0f4b19f61275397975.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/921d4093424b96601b05beaa7547bddd.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b6f7102d9b67a40253f390e32ea4d0e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/99abd5e15f2d2f94fb4285748597ba02.png)
过长方形土地的长边上离一端
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9b6363a9c7ab19b53bc1ddae6521a30a.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/e52b4f76eec4d4d212bfa6e3cfb9ebc2.png)
较小的一块土地种乙种作物,其面积为:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1b424d27e6609a62b48aafdfa45c8182.png)
![](https://img.xkw.com/dksih/QBM/editorImg/2022/10/6/ed8bd427-d245-4c1d-bb89-02b14b8cfe4c.png?resizew=708)
(1)【尝试应用】同学们从以上解决方法得到启发提出解决上述问题的另一思路:
若按如图2所示,划分出一块三角形土地
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/1885efcff0b903e314057dd153578600.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d50703c46b6153945d718b198f03b4b5.png)
(2)【拓展应用】现要把另一块长
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/92f256afee1098dac22f423b19b43c89.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/03902478df1a55bc99703210bccab910.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f631cfdf4666db95beb923072ced8d95.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6233fd10af2c8f3c6a1c3f9e318cda5d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/79cab1028086a4460003f192d12c58e0.png)
更新时间:2022-05-31 11:12:12
|
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解答题-问答题
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名校
【推荐1】将一副直角三角板按如图1摆放在直线AD上(直角三角板OBC和直角三角板MON,
,
,
,
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.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f7e38f2e04d304e1a362c9c2113bfb51.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2bfb836792b1eebfbd08a6f46fae580e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/3a563c50a7f6d10fa46339d7107fc85e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acfd93fa61a0e684e48131caae63a0bf.png)
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(1)如图2,当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/825116eb345f5505ebc8c1cdb8a1f131.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9fed1f57a835af4e9022e27603d12d31.png)
(2)继续旋转三角板MON,如图3,使得OM、ON同时在直线OC的右侧,猜想
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/32a89a0850a156bef223fba4d9609156.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f92f279be7c8a11dcd2c0a97116bdcbb.png)
(3)直线AD的位置不变,若在三角板MON开始顺时针旋转的同时,另一个三角板OBC也绕点O以每秒6°的速度顺时针旋转,当ON旋转至射线OD上时,两个三角板同时停止运动,当t多少秒时,
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dd98ca37454de0fb62a445dd2ae0978a.png)
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【推荐2】数轴上点A对应的数为a,点B对应的数为b,且多项式6x3y-2xy+5的二次项系数为a,常数项为b
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(2) 数轴上点P对应的数为x,若PA+PB=20,求x的值
(3) 若点M从点A出发,以每秒1个单位长度的速度沿数轴向右移动;同时点N从点B出发,以每秒2个单位长度的速度沿数轴向左移动,到达A点后立即返回并向右继续移动,求经过多少秒后,M、N两点相距1个单位长度
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【推荐1】某商场要经营一种新上市的文具,进价为
元
件,试营业阶段发现:当销售单价是
元时,每天的销售量为
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(件)与销售单价
(元)之间的函数关系式;
(2)求出商场销售这种文具,每天所得的销售利润
元与销售单价
(元)之间的函数关系式(不必写出
的取值范围);
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元,且每天的销售量不得少于
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/4333bb203d02814c146ed587b69ea69d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9c06fc7811f9525e8b8c833746d6af5c.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f38eed00a39aae5a7232b72a4d3ed821.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/bdaa19de263700a15fcf213d64a8cd57.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d07ae0b4264da6a8812454ffd2f20d94.png)
(1)请直接写出每天销售量
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)求出商场销售这种文具,每天所得的销售利润
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/595044a7750ab4f84519041979c3d780.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
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【推荐2】在平面直角坐标系中,抛物线
:
(
为常数)的顶点为
.
(1)若点
在第一象限,且
,求此抛物线所对应的二次函数的表达式,并直接写出函数值
随
的增大而减小时
的取值范围;
(2)当
时,若函数
的最小值为
,求
的值;
(3)分别过点
、
作
轴的垂线,交抛物线的对称轴于点
、
.当抛物线
与四边形
的边有两个交点时,将这两个交点分别记为点
、点
,且点
的纵坐标大于点
的纵坐标.
①若
时,求
值;
②点
为抛物线顶点,且不与点
重合,当点B到y轴距离与点C到x轴距离相等时,求
的值.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/a0ed1ec316bc54c37c4286c208f55667.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/186d49a7ee0530570ace9a51a5985833.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
(1)若点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/09d7ec20141db31e48d830a254370ad7.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
(2)当
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6a19d18f5b828cf554f352ec2a3434fa.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/186d49a7ee0530570ace9a51a5985833.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5ca7d1107389675d32b56ec097464c14.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
(3)分别过点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/2719ce8a1c0aaa60da102db5712d63e3.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9cb430483cb8dcb560569f5b761d8bb6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.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/a0ed1ec316bc54c37c4286c208f55667.png)
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![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
①若
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c23277437180df4cbfa3eec2bd186a48.png)
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②点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/c5db41a1f31d6baee7c69990811edb9f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/294f5ba74cdf695fc9a8a8e52f421328.png)
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【推荐1】如图,在平面直角坐标系中,直线
与坐标轴交于
两点,点
在
轴上,点
在
轴上,
,抛物线
经过点![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce7af7c5df749c6fa9bbe87faa72c66d.png)
![](https://img.xkw.com/dksih/QBM/2023/2/26/3182985991340032/3185763062292480/STEM/908c130902fc4d0a933e18628bc95d08.png?resizew=191)
(1)求抛物线的解析式;
(2)根据图象写出不等式
的解集;
(3)点
是抛物线上的一动点,过点
作直线
的垂线段,垂足为
,当![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b93284b0243b7dd327613b1cb42389d9.png)
时,求
点的坐标.
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/89c1972246a0a3d1c987d25205dbdd99.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/0ae6f48b9a53c0155a692509cf31f7e6.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/5963abe8f421bd99a2aaa94831a951e9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/81dea63b8ce3e51adf66cf7b9982a248.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/7f9e8449aad35c5d840a3395ea86df6d.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d053b14c8588eee2acbbe44fc37a6886.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/8642292b94b3039103cc578f555a8bbe.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9a0d44326c214c7a5ecc3068a29ec96f.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/ce7af7c5df749c6fa9bbe87faa72c66d.png)
![](https://img.xkw.com/dksih/QBM/2023/2/26/3182985991340032/3185763062292480/STEM/908c130902fc4d0a933e18628bc95d08.png?resizew=191)
(1)求抛物线的解析式;
(2)根据图象写出不等式
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/37247a896c05d47838f254d18ef63df1.png)
(3)点
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/f52a58fbaf4fea03567e88a9f0f6e37e.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/acc290b44635265137fdf13146b6a6d9.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/b93284b0243b7dd327613b1cb42389d9.png)
时,求
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/dad2a36927223bd70f426ba06aea4b45.png)
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【推荐2】如图,用一段长为30米的篱笆围成一个一边靠墙的矩形菜园ABCD,
(1)在墙的长度不限的条件下,当AB边长为多少米时,菜园的面积最大为多少?
(2)在墙的长度为14米的条件下,当AB边长为多少米时,菜园的面积最大为多少?
![](https://img.xkw.com/dksih/QBM/editorImg/2023/6/15/db7b546e-7bb0-4de9-b754-c9b5ab3e5a03.png?resizew=221)
(1)在墙的长度不限的条件下,当AB边长为多少米时,菜园的面积最大为多少?
(2)在墙的长度为14米的条件下,当AB边长为多少米时,菜园的面积最大为多少?
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