问道GRE
题目
问道GRE
For a project,a square piece of cloth is folded in half and swed together to form a rectangle that has a perimeter of 36 centimeters.what was the area in square centimenters of the piece of cloth before it was folded.
这个题我得出的答案是48,正确的答案是144,
答案
他求得是未折之前正方形面积
折成长方形后 周长36 说明正方形原来边长12
所以面积是144
举一反三
已知函数f(x)=x,g(x)=alnx,a∈R.若曲线y=f(x)与曲线y=g(x)相交,且在交点处有相同的切线,求a的值和该切线方程.
我想写一篇关于奥巴马的演讲的文章,写哪一篇好呢?为什么好
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