Chapter 12 - Vectors and the Geometry of Space - 12.3 Exercises - Page 830: 2

$2.2$

The dot product of two vectors $\mathbf a= \langle a_1,a_2 \rangle$ and $\mathbf b= \langle b_1,b_2 \rangle$ is $a_1b_1+a_2b_2$. So for $\mathbf a= \langle -2,3 \rangle$ and $\mathbf b= \langle 0.7,1.2 \rangle$, $$\mathbf a \cdot \mathbf b =(-2)(0.7)+3(1.2)=-1.4+3.6=2.2.$$