### Home > PC > Chapter 12 > Lesson 12.1.1 > Problem 12-9

12-9.

Let

and . Homework Help ✎ Find

*MN*.Find values for

*a*,*b*,*c*, and*d*so that*MN*=*I*.Use the results of (b) to find

*M*^{−1}.

Using the lower left entry from part (a) and matrix *I*:

−1(*a*) + 2(*c*) = 0

Now repeat this process for the rest of the entries.

Look at part (b) and remember that *M*(*M*^{−1}) = *I*.