Echelon Form

> **pivot（主元）**: The first non-zero entry of a row - 全零行一定在最后 - 下面的pivot一定在上面的pivot右边 - pivot下面都是0

Reduced Echelon Form

• 每个pivot都是1 • 每个pivot都是一列中唯一的非零数字

Each Matrix is row equivalent to **one and only one** reduced echelon matrix