Find the length of the curve. r(t)=<8t, t^2, \frac{1}{12} t^3> , 0 \leq t \leq 1

Find $\frac{dw}{dt}$ using the appropriate Chain Rule. Evaluate $\frac{dw}{dt}$ at the given value of t. Function: $w=x\sin y,x=e^t,y=\pi -t$ Value: $t=0$

Can 2 different ODE's have the same set of solutions?
If I have two differents linear ODE's:
$x^{\text{'}\text{'}}+p\left(t\right)x^{\text{'}}+q\left(t\right)x=f\left(t\right).p,q\in C(I,\mathrm{\infty }).$

$x^{\text{'}\text{'}}+j\left(t\right)x^{\text{'}}+g\left(t\right)x=h\left(t\right).j,g\in C(I,\mathrm{\infty }).$
Coul they have exactly the same set of solutions?
And if we have two different non-linear ODE's could they?