inverse of a function

例句：

1. 1.The inverse of the equation is x = 2.
   这个方程的逆是x=2。
2. 2. The inverse of the function f(x) is g(x)=-f(-x).
   函数f(x)的逆是g(x)=-f(-x)。
3. 3.The inverse of the matrix A is B if and only if B is an inverse of A.
   矩阵A的逆是B，仅当B是A的逆。