TI-Nspire CX II field manual for IB Math
Determinant and inverse of a matrix
Enter a matrix A, compute detA to confirm it is invertible, then compute A−1.
For C=⎣⎡210121012⎦⎤, find det(C) and C−1.
Store the matrix: type c:= with , insert a 3 x 3 matrix template with → 7: Matrix & Vector → 1: Create → 1: Matrix — in the dialog, type to set the rows and columns ( moves between the fields; the arrows change the numbers instead). Fill the entries 2, 1, 0, 1, 2, 1, 0, 1, 2 (move between cells with ), and press .
Compute the determinant: press → 7: Matrix & Vector → 3: Determinant to paste det(, type , and press .
The determinant is nonzero, so the inverse exists. Type , raise it to the power −1 (press then ), and press . The Nspire returns the inverse with exact fractional entries.
det(C)=4 and C−1=41⎣⎡3−21−24−21−23⎦⎤=⎣⎡43−2141−211−2141−2143⎦⎤.
Your turn
Work each one on your calculator, then check the answer.
- 1
For A=⎣⎡211121112⎦⎤, find det(A) and A−1.
- 2
For B=⎣⎡310121012⎦⎤, find det(B) and B−1.
- 3
For C=⎣⎡102210031⎦⎤, find det(C) and C−1.