CPM Homework Help : A2C Problem 7-218

Show that each of the following pairs of matrices are inverses.

$\left[ \begin{array} { c c } { 1 } & { 2 } \\ { 3 } & { 4 } \end{array} \right] \text { and } \left[ \begin{array} { c c } { - 2 } & { 1 } \\ { 1.5 } & { - 0.5 } \end{array} \right]$

Hint (a):

Remember to multiply the rows of the first matrix by the columns of the second one.

More Help (a):

Remember that matrices are inverse, if their product equals .

Answer (a):

These matrices are inverse.

$\left[ \begin{array} { c c } { 4 } & { - 5 } \\ { - 3 } & { 4 } \end{array} \right] \text { and } \left[ \begin{array} { c c } { 4 } & { 5 } \\ { 3 } & { 4 } \end{array} \right]$
Hint (b):
See part (a).