[swishin13]

Here is my problem:

given vectors
u=-i-5j and v=-2i+7j, find 9u-8v

I for the most part have been getting the vector questions but this one has me stumped. Should I multiply 9(-1-5) and 8(-2+7). Then subtract the two of them. I have tried doing that and the answer does not come up.

Any help is apprectiated thanks.

[Capuchin]

You need to keep the is and js in, and treat them like any other variable (in this case they are unit vectors).

so you need:



from here you can do the arithmetic, but you can see what I've done, I've kept the i and j and treated them separately, just like you would treat x and y separately.

Hope this helps :)

[Evil dead]

If you did not understand what Capuchin said, basically:

9(-i - 5j) - 8(-2i + 7j)

Multiply out the brackets, and then solve by: adding like terms, or subtracting like terms as stated in the question.

You have to treat the vectors as normal terms that can be multiplied.