Karim M. answered 05/01/20
Helping you succeed is my priority
du/dt=e2u+4t
du/dt=e2u * e4t
du/e2u= e4t dt
∫ e-2u du= ∫ e4t dt
-1/2 e-2u = 1/4 e4t +C
e-2u= -1/2 e4t +C
ln e-2u= ln (-1/2 e4t +C)
-2u = ln (-1/2 e4t +C)
u=( ln (-1/2 e4t +C)) /-2
u(0) =12= (ln(-1/2 +C)) /-2
e-24= = -1/2 +C
C= 0.5
u=( ln (-1/2 e4t +1/2)) /-2
i hope it was clear!