100分求一道数学题,

题目

100分求一道数学题,
After t years the population of a certain town is P(t) = 50+5t thousand people.A populationP has an associated CO2 level,C(P) = (根号下（P2 + 1）)/2.After 2 years,the rate at which CO2 level is changing with respect to t will be:答案是150/根号下3601 实在闹不明白为什么,
C(P) = (根号下（P2 + 1）)/2.P后面的2表示P的平方

答案

P（t）=50+5tC（p）=(根号下（P2 + 1）)/2.求的是变化率C（p）=[根号下（50+5t）²+1]/2=[根号下（2501+500t+25t²）]/2dC/dt=(500+50t)/｛4[根号下（2501+500t+25t²）]｝当t=2的时候dC/dt=（500+100）...