行列式の計算など | 1 1 X | | 1 X 1 | | X 1 1 | | 1 1 X |= | 1 1 X | = |X-1 1-X | | 1 X 1 | | 0 X-1 1-X | |1-X 1-X^2| | X 1 1 | | 0 1-X 1-X^2| =(1-x)^2 | -1 1 | = -(x+2)(1-x)^2 | 1 1+x |