cant you do t+10 for the other one starting before aswell?
In theory, yes; however, in reality no. Note that in the question it states "the value of the two paintings will be the same T years after 1991" - this is why you take T-10. If you take it as T+10, you end up with lnq^10 - ln2 = Tlnp/q but you don't know what q^10 is so you're screwed :P. If you use T-10 then you end up with a p^10 which you know from bi. = 5.
In theory, yes; however, in reality no. Note that in the question it states "the value of the two paintings will be the same T years after 1991" - this is why you take T-10. If you take it as T+10, you end up with lnq^10 - ln2 = Tlnp/q but you don't know what q^10 is so you're screwed :P. If you use T-10 then you end up with a p^10 which you know from bi. = 5.
oh when it says "the value of the two paintings will be the same T years after 1991"
it is basically telling you to put it starting at 1991... if you put t+10 then it may have been the same in that 10 year period you deleted!!
it would have asked... t years after 2001 then it would have been correct
typically its when you are told to find the angle between two lines. Be sure to dot the direction vectors if you are dealing with two vector equation of lines.
typically its when you are told to find the angle between two lines. Be sure to dot the direction vectors if you are dealing with two vector equation of lines.
Right! Could you explain that a bit more, I do seem to get the questions right but how to you know for certain to dot lets say AP . CD = 0, or with the line direction vector is there some kind of rule you have to notice?
Right! Could you explain that a bit more, I do seem to get the questions right but how to you know for certain to dot lets say AP . CD = 0, or with the line direction vector is there some kind of rule you have to notice?
The scalar product = 0 if they're perpendicular and as such if you're told that AP-> is perpendicular to CD-> you know you'll probably need to use the scalar product to find the answer they want.