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# Essential Linear Algebra for Data Science Coursera Quiz Answers

## Get Essential Linear Algebra for Data Science Coursera Quiz Answers

Are you interested in Data Science but lack the math background for it? Has math always been a tough subject that you tend to avoid? This course will teach you the most fundamental Linear Algebra that you will need for a career in Data Science without a ton of unnecessary proofs and concepts that you may never use. Consider this an expressway to Data Science with approachable methods and friendly concepts that will guide you to truly understanding the most important ideas in Linear Algebra.

This course is designed to prepare learners to successfully complete Statistical Modeling for Data Science Application, which is part of CU Boulder’s Master of Science in Data Science (MS-DS) program.

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#### Quiz 1: Practice – Linear System -> Matrix Format

Q1. Transfer the following linear system into matrix notation: x+2yz=4y+8z=0xy+z=−2

• ⎡​101​21−1​−181​40−2​​⎦⎥⎤​
• ⎡​101​21−1​−181​​⎦⎥⎤​

#### Quiz 2: LS -> Matrix + G.E. Full Question Quiz

Q1. T​ransfer the linear system into matrix notation and apply Gaussian Elimination. Does it have no solutions, one solution, or infinite solutions? What is the solution (unless no solution exists) xy+z=13y−2z=−52x−2y=−6

• I​nfinite Solutions
• x=−2 y=1y=1 z=4z=4
• N​o solution
• x=2 y=1y=1 z=-3z=−3

#### Quiz 1: Quiz on Matrix Algebra Sum + Scale

Q1. G​iven the matrices:

A =

[2−13−1]A=[2−1​3−1​], B =

[−25−4−1]B=[−25​−4−1​]

F​ind A+BA+B:

• A+B=[04​−1−2​]
• A+B=[04​−10​]

Q2. U​sing the same AA, BB matrices, find A-BAB:

• AB=[04​−1−2​]
• AB=[4−6​70​]

Q3. U​sing the same AA, BB matrices, find 3A3A:

• 3A=[32​3−1​​13−1​​]
• 3A=[6−3​9−3​]

Q4. U​sing the same AA, BB matrices, what is the row 1, column 1 entry of the matrix resulting from 3A-B3AB?

Answer: 

#### Quiz 2: Matrix Multiplication

Q1. C​onsider the matrices:

A =

⎡⎣5−27320141⎤⎦

A=⎣⎢⎡​5−27​320​141​⎦⎥⎤​, B =

⎡⎣29−3⎤⎦B=⎣⎢⎡​29−3​⎦⎥⎤​

C​an we multiply A \cdot BAB? If so, compute the resulting matrix.

• Y​es, and the resulting matrix is A \cdot B = ⎡⎣34211⎤⎦AB=⎣⎢⎡​34211​⎦⎥⎤
• N​o, the matrix dimensions of AA and BB are not compatible to perform A \cdot BAB.
• Y​es, and the resulting matrix is A \cdot B = ⎡⎣10−18−216180236−3⎤⎦AB=⎣⎢⎡​10−18−21​6180​236−3​⎦⎥
• Y​es, and the resulting matrix is A \cdot B = ⎡⎣3402⎤⎦AB=⎣⎢⎡​3402​⎦⎥
• Y​es, and the resulting matrix is A \cdot B = ⎡⎣37211⎤⎦AB=⎣⎢⎡​37211​⎦⎥⎤

Q2. C​onsider the same AA, BB matrices:

C​an we multiply B \cdot ABA? If so, compute the resulting matrix.

• Y​es, and the resulting matrix is B \cdot A = ⎡⎣10−18−216180236−3⎤⎦ BA=⎣⎢⎡​10−18−21​6180​236−3​⎦⎥⎤​
• N​o, the matrix dimensions of AA and BB make B \cdot ABA impossible to compute.
• Y​es, and the resulting matrix is B \cdot A = ⎡⎣34211⎤⎦BA=⎣⎢⎡​34211​⎦⎥

Q3. S​ay we have the matrices D_{3×1024}D3x1024​ and C_{1024×8}C1024x8​, how many columns would the matrix resulting from D \cdot CDC have?

Answer: 

#### Quiz 1: Why do we use matrices and vectors and not just one?

Q1. D​etermine if the following statement is true or false:

V​ectors are useful as they can show us the direction that something is moving in and have applications to computing things like velocity.

• True
• False

Q2. D​etermine if the following statement is true or false:

A​ vector is not a matrix.

• True
• False

#### Quiz 2: Quiz on Linear Independence

Q1. C​onsider the following:

x =

⎡⎣123⎤⎦x=⎣⎢⎡​123​⎦⎥⎤​, y =

⎡⎣321⎤⎦y=⎣⎢⎡​321​⎦⎥⎤​, z =

⎡⎣048⎤⎦z=⎣⎢⎡​048​⎦⎥⎤​

Are {x,y,zx,y,z} linearly independent?

• Yes
• No

#### Quiz 3: Quiz on Transformations and Inverse

Q1. F​ind the inverse of A, where A =

⎡⎣70−32341−1−2⎤⎦A=⎣⎢⎡​70−3​234​1−1−2​⎦⎥

• A−1=⎣⎢⎡​9−646​−618−34​91735​⎦⎥
• A−1=⎣⎢⎡​649​8−5−34​−5921​⎦⎥⎤​
• A−1=⎣⎢⎡​−239​8−11−34​−5721​⎦⎥
• A−1=⎣⎢⎡​769​8−714​−5921​⎦⎥

#### Quiz 1: Find the Determinant of a 2×2 Matrix

Q1. F​ind the determinant of the matrix A =

[219−3]A=[21​9−3​]

Answer: 

#### Quiz 2: Find Eigenvalue then Eigenvector of a Matrix (2×2)

Q1. F​ind the eigenvalues of the matrix:

A =

[0−21−3]A=[0−2​1−3​]

Answer: 

Q2. F​ind the corresponding eigenvectors from Question 1:

• [11​]
• [1−2​]
• [1−1​]
• [−12​]
• [−11]

#### Quiz 3: Find Eigenvalue then Eigenvector of a Matrix (3×3)

Q1. F​ind the eigenvalues of the matrix:

A =

⎡⎣52−3254006⎤⎦A=⎣⎢⎡​52−3​254​006​⎦⎥⎤

Answer: 

Q2. F​ind the corresponding eigenvectors from Question 1:

• ⎡​111​⎦⎥⎤​
• ⎡​110​⎦⎥
• ⎡​2−10​⎦⎥⎤​
• ⎡​3−37​⎦⎥⎤​
• ⎡​001​⎦⎥⎤​
• ⎡​2−37​⎦⎥⎤​

#### Quiz 1: Important Final Concepts

Q1. C​ompute the dot product of the vectors u =

⎡⎣324⎤⎦u=⎣⎢⎡​324​⎦⎥⎤​ and v =

⎡⎣206⎤⎦v=⎣⎢⎡​206​⎦⎥⎤​, recall that u^{T}v=v^{T}uuTv=vTu.

Answer: 

Q2. C​ompute the norm of the vector ||v||∣∣v∣∣, where v =

⎡⎣⎢⎢2222⎤⎦⎥⎥

v=⎣⎢⎢⎢⎡​2222​⎦⎥⎥⎥⎤​:

Answer: 

Q3. F​ind the distance between the vectors u =

⎡⎣324⎤⎦u=⎣⎢⎡​324​⎦⎥⎤​ and v =

⎡⎣152⎤⎦v=⎣⎢⎡​152​⎦⎥⎤​:

• 17​
• 1​7
• 4
• 15

#### Quiz 2: Finding Least Squares Solutions

Q1. F​ind the least squares solution to Ax=bAx=b using :

A =

⎡⎣⎢⎢1111−6−217⎤⎦⎥⎥A=⎣⎢⎢⎢⎡​1111​−6−217​⎦⎥⎥⎥⎤​ and b =

⎡⎣⎢⎢−1216⎤⎦⎥⎥b=⎣⎢⎢⎢⎡​−1216​⎦⎥⎥⎥

• x^=[121​​]
• ^=[−331​​]
• ^=[221​​]

#### Quiz 3: Final Exam

Q1. F​or the matrices A =

[20241−2]A=[20​24​1−2​], B =

⎡⎣7−1−7616⎤⎦B=⎣⎢⎡​7−1−7​616​⎦⎥⎤​, find C=ABC=AB.

W​hat is the number in matrix CC‘s row 2, column 2?

Answer: 

Q2. F​ind the determinant of A =

[9−5−110]

A=[9−5​−110​]:

Answer: 

Q3. F​ind the eigenvalues for

[7034]

[70​34​]:

Answer: 

Q4. C​ompute the dot product of u =

⎡⎣79−2⎤⎦u=⎣⎢⎡​79−2​⎦⎥⎤​ and v =

⎡⎣10−320⎤⎦v=⎣⎢⎡​10−320​⎦⎥⎤​:

• 3
• -3
• 10
• 83

Q5. U​sing Gaussian Elimination, solve the following system of equations:

3x+4y+4z=36x+8y+4z=62y+2z=4

U​sing a calculator round any remaining fractions to the nearest hundredth.

• x=1.67 y=2y=2 z=0z=0
• x=−3 y=-2y=−2 z=0z=0
• x=−1.67 y=2y=2 z=0z=0
• x=0 y=4y=4 z=4z=4

Q6. A​re the vectors u =

⎡⎣05−4⎤⎦u=⎣⎢⎡​05−4​⎦⎥⎤​ and v =

⎡⎣15−4−5⎤⎦v=⎣⎢⎡​15−4−5​⎦⎥⎤​ orthogonal?

• Yes
• No

Q7. F​ind the inverse of AA, where A =

⎡⎣103826422⎤⎦A=⎣⎢⎡​103​826​422​⎦⎥⎤​.

R​ound any fractions to the nearest hundredth in your solution.

• A−1=⎣⎢⎡​.5.38−.38​−.5−.631.13​−.5−.13.13​⎦⎥
• A−1=⎣⎢⎡​−.5.38−.38​.5−.631.13​.5−.13.13​⎦⎥⎤
• A−1=⎣⎢⎡​−.17.38−.5​.25.631.11​.35.17.11​⎦⎥⎤​

Q8. F​ind the least squares solution to Ax=bAx=b using:

A =

⎡⎣⎢⎢.1.1.1.1−.6−.2.1.7⎤⎦⎥⎥A=⎣⎢⎢⎢⎡​.1.1.1.1​−.6−.2.1.7​⎦⎥⎥⎥⎤​ and b =

⎡⎣⎢⎢−.1.2.1.6⎤⎦⎥⎥b=⎣⎢⎢⎢⎡​−.1.2.1.6​⎦⎥⎥⎥⎤​

H​int: This problem can be made easier by scaling AA and bb so they are no longer decimals.

• x^=[12​]
• ^=[331​​]
• ^=[1−1​]
• ^=[221​​]
##### Conclusion:

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