$5-12$ Use Formula

$(3)$ to find $x(n).$

Solve $8$ and $10$

$5.r(t)=t^{2}i+t^{3}j$

$6.r(t)=2sint{t}^{}+8costj$

$7.r(f)=e^{3-1}+e^{-1}j$

$9.$

e$.r(t)=\frac{1-t^2}{t^2+1}i+\frac{2t}{t^2+1}j$

$10.r(t)=3ti+3t^{2}j+2t^{3}k$

$11.x=$ cosh $t,y=$ sithos, $z=t$

$12.r(t)=1i+j+\sqrt[\phantom{2}]{ik}$