# Math Help - Simplifying Dot product

1. ## Simplifying Dot product

Regarding question 9 a) why is this the answer and not
Also why is a part of the answer in the book: 7 a (Dot) b not 7 |a| |b| like the other expressions in the answer from the book?

2. ## Re: Simplifying Dot product

Looks to me like your answer is the same as the one in the book, with the exception that you have a term of $7\vec a \vec b$, by which I assume you mean $7|\vec a| \vec b|$, whereas the book's answer is $7 \vec a \cdot \vec b$. The reason the book has the dot product is that $\vec a$ and $\vec b$ are not necessarily orthogonal, the way perhaps other examples in your book may be.