Consider a system with input $u$ and output $y.$ Three experiments are performed on the system using the inputs $u_1(t),u_2(t),$ and $u_3(t)$ for $t0.$ In each case, the initial state $x(0)$ at time $t=0$ is the same. The corresponding outputs are denoted by $y_1,y_2,$ and $y_3.$ Which of the following statements are correct if $x(0)0?$

If $u3=u1+u2,$ then $y3=y1+y2.$

If $u3=0\mathrm{.}5(u1+u2),$ then $y3=0\mathrm{.}5(y1+y2).$

If $u3=ul-u2,$ then $y3=yl-y2.$