Chapter 3.1, Problem 21E

In Exercises 19–24, explore the effect of an elementary row operation on the determinant of a matrix. In each case, state the row operation and describe how it affects the determinant.

21. $\left[\begin{array}{cc}\text{a}& \text{b}\\ \text{c}& \text{d}\end{array}\right],\left[\begin{array}{cc}\text{a}& \text{b}\\ \text{kc}& \text{kd}\end{array}\right]$