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Chapter 4. Vector Spaces. Linear Algebra. 4.1 General Vector Spaces. Our aim in this section will be to focus on the algebraic properties of R n. Definition
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Chapter 4 Vector Spaces Linear Algebra
4.1 General Vector Spaces Our aim in this section will be to focus on the algebraic properties of Rn. • Definition • A ……………… is a set V of elements calledvectors, having operations of addition and scalar multiplication defined on it that satisfy the following conditions: • Let u, v, and w be arbitrary elements of V, and c and d are scalars. • Closure Axioms • u + v…………… (V is closed under addition.) • cu …………… (V is closed under scalar multiplication.)
Definition of Vector Space (continued) • Addition Axioms • 3. u + v = …………… (commutative property) • 4. u + (v + w) = …………… (associative property) • 5. There exists an element of V, called the…………, denoted 0, such that u + 0 =…… • 6. called the……… of u, such that u + (-u) = 0. • Scalar Multiplication Axioms • 7.c(u + v) = …………… • 8. (c + d)u =…………… • c(du) = …………… • 1u = ……………
Example 1 A Vector Space in R3 Is V a vector space ? Solution Example 2 Is Z a vector space ? Solution Ch04_4
Prove that W is a vector space. Example 3 Proof
Vector Spaces of Matrices (Mmn) Prove that M22 is a vector space. Proof
In general: The set of m n matrices, Mmn, is a vector space.
Example 4 Solution Ch04_8
Vector Spaces of Functions Prove that F = { f | f : RR } is a vector space.
Vector Spaces of Functions (continued) Example 5 Is the set F={ f | f (x)=ax2+bx+c , a,b,cR , } a vector space? Solution Ch04_11
Subspaces Definition Let V be a vector space and U be a …………………………. of V. U is said to be a …………… of V if it is ……………………….. and ………………………………….. Note:
Example 6 Let U be the subset of R3 consisting of all vectors of the form (a, a, b) , a,bR , i.e., U = {(a, a, b) R3 }. Show that U is a subspace of R3. Solution Show that U = {(a, 0, 0) R3 , aR} is a subspace of R3.
Example 7 Let V be the set of vectors of of R3 of the form (a, a2, b), V = {(a, a2, b) R3 , a,bR}. Is V a subspace of R3 ? Solution
Example 8 Prove that the set W of 2 2 diagonal matrices is a subspace of the vector space M22. Solution Ch04_15
Theorem 4.5 (Very important condition) Let U be a subspace of a vector space V. ……………………………………… Example 9 Let W be the set of vectors of the form (a, a, a+2). Show that W is not a subspace of R3. Solution