## College Algebra (6th Edition)

$A^{-1}=\left[\begin{array}{lll} 1 & 1 & 1\\ 3 & 5 & 4\\ 3 & 6 & 5 \end{array}\right]$
Technology used: the free online calculator at www.geogebra.org/classic/cas The syntax for defining a matrix: A:= { { row 1}, {row 2} ... { row n} }, (the elements in rows are delimited with commas) (A "colon equals" assigns the matrix to A). The command for $B=A^{-1}$ is B:= Invert ( A ). (B "colon equals" assigns the matrix to B). Check by multiplying the matrices AB=BA=I Please see screenshot below. $A^{-1}=\left[\begin{array}{lll} 1 & 1 & 1\\ 3 & 5 & 4\\ 3 & 6 & 5 \end{array}\right]$