If a = t^2 i - (4-t)j(adsbygoogle = window.adsbygoogle || []).push({});

and b = i + t j

show d/dt (a.b) = (a x db/dt) + (da/dt x b)

I know you have to multiply the vectors a and b

then do da/dt

then db/dt

and times db/dt with a

and times da/dt with b

that should be the proof

However, I don't know how to multiply the vectors!

Can someone please tell me how to multiply them

Thank you, in advance

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Multiplying vectors

**Physics Forums | Science Articles, Homework Help, Discussion**