PLAN 490 Lecture : rup 490_jan 29 1-3.pdf

dy/dt - 2y = y^-8 i keep solving thisquestion and getanswer y=(1/2+ce^(-18t))^(1/9)and I want to know what is the correct answer for this. this isBernoulli question.

Show that if u, v, w, and r are any vectors, then

a. u χ ( v χ w) + v χ ( w χ u) + w χ ( u χ v) = 0

b. u χ v = (u · v χ i)i + (u · v χ j)j + (u · v χ k)k

c. ( u χ v) · ( w χ r) =

I believe I have the first part worked out:
U=mgh --> U=980 K+U=0 --> K= -980
-980=.5(20)(v^2) --> v=9.9 m/s
But I have no idea where to go on the second part.