What it means
A superscript −1 means the inverse: for a number, its reciprocal; for a matrix, the matrix that multiplies with it to give the identity; for a function, the function that undoes it. sin⁻¹ x is the arcsine, not one over sin x.
Read aloud in real formulas
AA⁻¹ = I
Aethel says
A A inverse equals I
a matrix times its inverse is the identity
β̂ = (XᵀX)⁻¹Xᵀy
Aethel says
beta hat equals the quantity X transpose X, inverse, times X transpose y
the least-squares coefficients
Typing it
- LaTeX
- A^{-1}
- Unicode
- U+207B U+00B9
Formulas that use it
Questions
How do you say ⁻¹ out loud?
It is usually read “inverse”, and also “to the power of negative one”.
What does ⁻¹ mean in maths?
A superscript −1 means the inverse: for a number, its reciprocal; for a matrix, the matrix that multiplies with it to give the identity; for a function, the function that undoes it. sin⁻¹ x is the arcsine, not one over sin x.
How do you type ⁻¹?
In LaTeX, write A^{-1}. Its Unicode code point is U+207B U+00B9.