## Calculus (3rd Edition)

(c) $v\cdot \langle -3,0,0 \rangle$ is equal to zero for all choices of $v$.
Since $v$ lies in $yz$-plane, then it will take the form $\langle 0,a,b \rangle$. (a) $v\cdot \langle 0,2,1 \rangle =\langle 0,a,b \rangle\cdot \langle 0,2,1 \rangle=2a+b\neq 0$ for some $a,b$ . (b) $v\cdot k =\langle 0,a,b \rangle\cdot \langle 0,0,1 \rangle=b\neq 0$ for some $b$. (c) $v\cdot \langle -3,0,0 \rangle=-3*0+0*a+0 *b=0$ for all choices of $v$. (b) $v\cdot j =\langle 0,a,b \rangle\cdot \langle 0,1,0 \rangle=a \neq 0$ for some $a$.