How do I enter a matrix on a TI-84?

Press 2nd + x^-1 (MATRIX), go to EDIT, pick [A], set the rows and columns, then type each number followed by ENTER. Press 2nd + MODE (QUIT) when you are done.

What does DIM MISMATCH mean?

Your matrices have incompatible sizes. For addition and subtraction, both matrices must have identical dimensions. For multiplication, the columns of the first must equal the rows of the second.

How do I multiply two matrices on a TI-84?

From the home screen, select [A] from the MATRIX NAMES menu, type the multiply key, select [B], and press ENTER. Check dimensions first to avoid DIM MISMATCH.

How do I find the inverse of a matrix?

Select [A], press the x^-1 key, and hit ENTER. The matrix must be square with a non-zero determinant — otherwise you will get a SINGULAR MATRIX error.

How do I find a determinant on a TI-84?

Go to MATRIX → MATH → det(, select your matrix, close the parenthesis, and press ENTER. Example: det([A]).

How do I solve a system of equations with matrices?

Write the system as AX = B, where A holds the coefficients and B the constants. Enter both matrices, then compute [A]^-1 × [B]. The result is the solution vector.

How do I clear a matrix?

Go to MATRIX → EDIT, select the matrix, and press CLEAR. Or from the home screen, use the Mem menu (2nd + +) to reset all matrices at once.

TI-84 Matrix Operations

Matrices without the headache. Enter, add, multiply, invert.

Matrices show up in Algebra 2 and pre-calculus, and the TI-84 handles the tedious arithmetic for you. Here is every operation, step by step.

The six core operations

1Open the matrix editor
Press 2nd + x^-1 (the MATRIX key). Arrow right to EDIT, then press ENTER on [A]. Type the number of rows, press ENTER, type the number of columns, press ENTER.
2Type in your numbers
Enter each value and press ENTER after it. The cursor moves through the matrix automatically. When every slot is filled, press 2nd + MODE (QUIT) to go back to the home screen.
3Add or subtract matrices
Press 2nd + x^-1, choose NAMES, and select [A]. Type +, then select [B] the same way. Press ENTER. Both matrices must have the same dimensions, or you will get a DIM MISMATCH error.
4Multiply matrices
Select [A], type ×, select [B], and press ENTER. Remember the rule: the number of columns in [A] must equal the number of rows in [B]. A 2×3 times a 3×2 gives a 2×2 result.
5Find an inverse
Select [A], then press the x^-1 key (not 2nd — just x^-1). Press ENTER. This computes A^-1, which only exists for square matrices with a non-zero determinant.
6Find a determinant
Press 2nd + x^-1, arrow to MATH, and choose det(. Then select [A], close the parenthesis, and press ENTER. A determinant of zero means the matrix has no inverse.

Errors you will meet (and what they mean)

DIM MISMATCH

The #1 matrix error. Your dimensions do not line up for the operation. Double-check the sizes: addition needs identical dimensions, multiplication needs columns-of-first = rows-of-second.

SINGULAR MATRIX

You asked for an inverse that does not exist. The determinant is zero, which means the matrix is singular. In a system of equations, this usually means no unique solution — check your original problem.

INVALID DIM

You tried to create a matrix with zero rows or columns, or referenced a matrix that was never defined. Re-enter the matrix in the editor and try again.

The system-of-equations shortcut

This is why matrices matter. A system like 2x + 3y = 8 and x − y = 1 becomes [A]×[X] = [B]. Enter the coefficient matrix as [A] and the constants as [B], then compute [A]^-1 × [B]. The answer pops out — no substitution slog.

Want to visualize systems instead? Our graphing guide shows how to find solutions where two graphs intersect.

Frequently asked questions

Last updated: September 26, 2026