A level
问题描述：
A level
a metal bar is heated to a certain temperature and then th heat source is removed .at time t minutes after the heat source is removed ,the temperature ,θ degrees clelsius ,of the metal bar is given by θ=280/1+0.02t,at what rate is the temperature decreasing 100 minutes after the removal of the heat source
答
温度函数为θ=280/(1+0.02t) t≥0(min)
在100分钟后,θ=280/(1+0.02*100)=93.33(度)