Chapter 6.CR, Problem 100CR

True or False? In Exercises 99-102, determine whether each statement is true or false. If a statement is true, give a reason or cite an appropriate statement from the text. If a statement is false, provide an example that shows the statement is not true in all cases or cite an appropriate statement from the text.

(a) Reflection that map a point in the xy-plane to its mirror image across the x-axis are linear transformations that are defined by the matrix $\left[\begin{array}{cc}1& 0\\ 0& -1\end{array}\right]$.

(b) Vertical expansions or contractions are linear transformations that are defined by the matrix $\left[\begin{array}{cc}1& 0\\ 0& k\end{array}\right]$.