用总长为60m的篱笆围成矩形场地,矩形面积S随矩形一边长a的变化而变化.当a是多少时,场地的面积S最大,最大面积是多少?
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/a463957e-fa2c-4fa4-b8cc-fdfbc5af337e.png?resizew=276)
解:
根据题意列方程:_________
整理后得:
(0<a<30),
当a=
=________ 时,S=
=_________ m2
当矩形一边长为15m时,场地的面积取最大值,且最大值为225m2
![](https://img.xkw.com/dksih/QBM/editorImg/2022/8/8/a463957e-fa2c-4fa4-b8cc-fdfbc5af337e.png?resizew=276)
解:
根据题意列方程:
整理后得:
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/d3c6e1d1261141242acc51a2f1b0a2ed.png)
当a=
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/9d3b268d9d6d4cc23f3692bad62a81e8.png)
![](https://staticzujuan.xkw.com/quesimg/Upload/formula/6715c0375923ac31c2fb6331c9dcf38b.png)
当矩形一边长为15m时,场地的面积取最大值,且最大值为225m2
更新时间:2021-08-30 16:56:19
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【知识点】 与图形有关的问题(一元二次方程的应用)解读
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