Calculation: HAmtvD - 1

ρ  = 
 ρ0* (1+ α* t)
ρ =  ρ0* (1+ α* t)$$\rho$$ = $$\rho0\cdot (1+\alpha\cdot t)$$
ρ = ρ0+ t* α* ρ0$$\rho$$ = $$\rho0+t\cdot \alpha\cdot \rho0$$