回答:
#Y = 24X-40#
说明:
特定 #X = F(t)的# 和 #Y =克(吨)#,我们可以将切线方程推广为
#Y =(G '(T))/(F'(t))的X +(G(t)的-f(t)的((G '(T))/(F'(T))))#
#DY / DX = DY / DT * DT / DX =(2T-2)*(2sqrtt)= 4(T-1)sqrtt#
#T = 4# 给我们:
#DY / DX = 4(4-1)= sqrt4 24#
#F(4)= sqrt4 = 2#
#G(4)= 4 ^ 2-2(4)= 8#
#8 = 2(24)+ C#
#C = 8-48 = -40#
#Y = 24X-40#