求问一道个人认为很难的数学题

automobiler

新东方上课时候发的讲义上面的。

The price of a bushel of corn is currently $3.20, and the price of a peck of wheat is $5.80. The price of corn is increasing at a constant rate of 5x cents per day while the price of wheat is decreasing at a constant rate of (根号2*x-x)cents per day. What is the approximate price when a bushel of corn costs the same amount as the peck of wheat?

 

 

The key is $5.6

对不起，根号2不知道咋输进来。高人帮忙解答一下吧，谢谢！

angelavivi

不是高人。

我的解法：3.2+5x = 5.8 - (根号2*x-x)   根号2 ~ 1.414  ===> x = 0.5

==> price  = 5.6 or 5.7

automobiler

答案有几个

A4.5

B5.1

C5.3

D5.5

E5.6

看来也没有巧妙的办法了？