Matriz Inversa 2×2

M⁻¹ = (1/det)·adj(M).
Created by
Renato Passos, Eng. de Software
Reviewed by
Renato Passos, Eng. de Software

Last updated: Apr 18, 2026

m11
0,600000
m12
-0,700000
m21
-0,200000
m22
0,400000

Formula

M⁻¹ = (1/det)·[[d,-b],[-c,a]]

About this calculator

This calculator finds the inverse of a 2×2 matrix. The inverse of a matrix M, denoted M⁻¹, is a matrix that when multiplied by M yields the identity matrix. For 2×2 matrices, the formula is M⁻¹ = (1/det)·[[d,-b],[-c,a]], where det = a*d - b*c. The determinant must be nonzero for the inverse to exist.

The calculation is done in two steps: first, compute the determinant (det = a*d - b*c). If det = 0, the matrix is singular and has no inverse. Otherwise, swap the elements on the main diagonal (a and d), change the signs of the secondary diagonal (b and c), and divide each element by the determinant.

Use this calculator when you need to solve 2×2 systems of linear equations, find inverse transformation matrices, or in geometry and physics problems involving rotations or reflections. It is useful for students of linear algebra, engineering, and computer graphics.

Caution: check that the determinant is not zero. If it is, the matrix has no inverse. Also, remember the order of elements in the formula: a goes to position d, and b becomes -b. Common mistakes include incorrect sign changes or forgetting to divide by the determinant.

Frequently asked questions

What happens if the determinant is zero?

If the determinant is zero, the matrix is singular and has no inverse. The calculator will display an error message.

Can I use this calculator for 3×3 matrices?

No, this calculator is specific to 2×2 matrices. For 3×3 matrices, you will need a different calculator.

How do I verify if the computed inverse is correct?

Multiply the original matrix by the obtained inverse. The result should be the 2×2 identity matrix: [[1,0],[0,1]].

What does the notation adj(M) mean?

adj(M) is the adjugate matrix, which for a 2×2 matrix is simply [[d,-b],[-c,a]]. It is the transpose of the cofactor matrix.

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