Question

帮我做一个线性代数的证明题：已知A是正交矩阵,A-I可逆,B=(A+I)(A-I)^-1 .证明B是反对称矩阵

Answer 1

证明:B^T=[(A+I)(A-I)^-1]^T = (A-I)^-1^T(A+I)^T ----知识点1 = (A-I)^T^-1(A+I)^T --知识点2 = (A^T-I^T)^-1(A^T+I^T) = (A^-1-I)^-1(A^-1+I) --知识点3 = (A^-1-I)^-1(A^-1A)(A^-1+I) = (I-A)^-1(I+A) = -(A-I)^-1(A+I) = -(A+I)(A-I)^-1 --知识点4 = -B.所以B是反对称矩阵.