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Grade 12 Math Lab: Analysis & Inference FREE
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Null Space & Linear Algebra Foundations
Learning Objectives
- Find null space of a matrix
- Understand rank-nullity theorem
- Solve homogeneous systems
Key Concepts
Null Space
Set of all vectors x where Ax = 0
Rank-Nullity
rank(A) + nullity(A) = number of columns
Theory
**Null Space** (kernel) of A: all solutions to Ax = 0
**To find:**
1. Row reduce A to RREF
2. Express free variables as parameters
3. Write solution as linear combination of basis vectors
**Rank-Nullity Theorem:** rank(A) + nullity(A) = n (# columns)
**Trivial null space:** Only x = 0 → columns are linearly independent.
Examples
Null space of [[1,2],[2,4]]
Solution: RREF: [[1,2],[0,0]]. x₁=-2x₂. Null space = span{⟨-2,1⟩}