6.【线性代数】—— 列空间和零空间[ c o l 11 c o l 21 c o l 31 c o l 12 c o l 22 c o l 32 c o l 13 c o l 23 c o l 33 ] ⏟ A [ a b c ] ⏟ x = a ∗ c o l 1 + b ∗ c o l 2 + c ∗ c o l 3 \underbrace{\begin{bmatrix} col_{11}&col_{21}&col_{31}\\ col_{12}&col_{22}&col_{32}\\ col_{13}&col_{23}&col_{3