## University Calculus: Early Transcendentals (3rd Edition)

We use the orthogonality test: $n \cdot v=\lt 2,1,0 \gt \cdot \lt 2,-4,1 \gt$ or, $=2(2)+1(-4)+0(1)$ or, $n \cdot v =0$ This implies that the vector $v$ is orthogonal to the plane's normal vector $n$. Hence, the vector is parallel to the plane because we have $n \cdot v =0$