Self Quiz 1 - Applied Linear Algebra | MATH 310, Quizzes of Linear Algebra

Material Type: Quiz; Class: Applied Linear Algebra; Subject: Mathematics; University: University of Illinois - Chicago; Term: Unknown 2012;

Typology: Quizzes

2011/2012

Uploaded on 05/18/2012

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MATH 310
Self-quiz 1
1. Let E3be the set of all triples of real numbers, i.e.:
E3={(a, b, c) : a, b, c real numbers}
We define addition in E3by:
(a1, b1, c1)+(a2, b2, c2)=(a1+a2, b1+b2, c1+c2)
and scalar multiplication by:
λ(a, b, c)=(λa, λb, λc)
Show that E3equipped with these two operations is a vector space.
2. In the vector space R2find a vector vwhich is such that:
pf3
pf4
pf5

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MATH 310

Self-quiz 1

  1. Let E^3 be the set of all triples of real numbers, i.e.:

E^3 = {(a, b, c) : a, b, c real numbers}

We define addition in E^3 by:

(a 1 , b 1 , c 1 ) + (a 2 , b 2 , c 2 ) = (a 1 + a 2 , b 1 + b 2 , c 1 + c 2 )

and scalar multiplication by:

λ(a, b, c) = (λa, λb, λc)

Show that E^3 equipped with these two operations is a vector space.

  1. In the vector space R^2 find a vector v which is such that:

3 v + 2u + w = 0

where u = (1, −1)T^ and w = (2, 1)T^.

This implies that:

((a 1 , b 1 , c 1 )+(a 2 , b 2 , c 2 ))+(a 3 , b 3 , c 3 ) = (a 1 , b 1 , c 1 )+((a 2 , b 2 , c 2 )+(a 3 , b 3 , c 3 ))

i.e. addition is indeed associative.

  • We can readily see that (0, 0 , 0) is the neutral element for addition i.e.:

(a, b, c) + (0, 0 , 0) = (a, b, c)

  • The additive inverse of (a, b, c) is (−a, −b, −c) because:

(a, b, c) + (−a, −b, −c) = (0, 0 , 0)

  • We can now check that

(λ + μ)(a, b, c) = λ(a, b, c) + μ(a, b, c)

Indeed each side equals (λa + μa, λb + μb, λc + μc) as can be easily seen by carrying out the computation

  • λ((a 1 , b 1 , c 1 ) + (a 2 , b 2 , c 2 )) = λ(a 1 , b 1 , c 1 ) + λ(a 2 , b 2 , c 2 ) Again in this case it is easy to check that each side equals:

(λa 1 + λa 2 , λb 1 + λb 2 , λc 1 + λc 2 )

  • It is immediate that 1(a, b, c) = (a, b, c)
  • Finally (λμ)(a, b, c) = λ(μ(a, b, c)) since each side equals:

(λμa, λμb, λμc)

So E^3 is indeed a vector space when equipped with the above operations.

  1. In the vector space R^2 find a vector v which is such that:

3 v + 2u + w = 0

where u = (1, −1)T^ and w = (2, 1)T^.

Solution: We can solve the given equation for v as follows:

3 v = − 2 u − w =⇒ v = −

3 u^ −^

3 w

By substituting u and w, we get:

v = −

3 (1,^ −1)

T − 1

3 (2,^ 1)

T =

3 ,^

)T