What is the magnitude of -2a - 3b when a=3i+9j and b=4i-6j?

Dot product of the 2 vectors = 0. Therefore cos x = 0 where j is the angle between the 2 vectors. S0 j = 90°... I believe.

the functions have the same rate of change i think. i narrowed it down to this answer and "the rate of change of tour 1 is greater" but i got it wrong using that answer so im assuming its the answer above. (this is a question i also answered from the iready site if anyone needs a reference)