1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Feliz [49]
2 years ago
9

Please determine whether the set S = x^2 + 3x + 1, 2x^2 + x - 1, 4.c is a basis for P2. Please explain and show all work. It is

fine to use technology.
Mathematics
1 answer:
ohaa [14]2 years ago
5 0

The vectors in S form a basis of P_2 if they are mutually linearly independent and span P_2.

To check for independence, we can compute the Wronskian determinant:

\begin{vmatrix}x^2+3x+1&2x^2+x-1&4\\2x+3&4x+1&0\\2&4&0\end{vmatrix}=4\begin{vmatrix}2x+3&4x+1\\2&4\end{vmatrix}=40\neq0

The determinant is non-zero, so the vectors are indeed independent.

To check if they span P_2, you need to show that any vector in P_2 can be expressed as a linear combination of the vectors in S. We can write an arbitrary vector in P_2 as

p=ax^2+bx+c

Then we need to show that there is always some choice of scalars k_1,k_2,k_3 such that

k_1(x^2+3x+1)+k_2(2x^2+x-1)+k_34=p

This is equivalent to solving

(k_1+2k_2)x^2+(3k_1+k_2)x+(k_1-k_2+4k_3)=ax^2+bx+c

or the system (in matrix form)

\begin{bmatrix}1&1&0\\3&1&0\\1&-1&4\end{bmatrix}\begin{bmatrix}k_1\\k_2\\k_3\end{bmatrix}=\begin{bmatrix}a\\b\\c\end{bmatrix}

This has a solution if the coefficient matrix on the left is invertible. It is, because

\begin{vmatrix}1&1&0\\3&1&0\\1&-1&4\end{vmatrix}=4\begin{vmatrix}1&2\\3&1\end{vmatrix}=-20\neq0

(that is, the coefficient matrix is not singular, so an inverse exists)

Compute the inverse any way you like; you should get

\begin{bmatrix}1&1&0\\3&1&0\\1&-1&4\end{bmatrix}^{-1}=-\dfrac1{20}\begin{bmatrix}4&-8&0\\-12&4&0\\-4&3&-5\end{bmatrix}

Then

\begin{bmatrix}k_1\\k_2\\k_3\end{bmatrix}=\begin{bmatrix}1&1&0\\3&1&0\\1&-1&4\end{bmatrix}^{-1}\begin{bmatrix}a\\b\\c\end{bmatrix}

\implies k_1=\dfrac{2b-a}5,k_2=\dfrac{3a-b}5,k_3=\dfrac{4a-3b+5c}{20}

A solution exists for any choice of a,b,c, so the vectors in S indeed span P_2.

The vectors in S are independent and span P_2, so S forms a basis of P_2.

You might be interested in
Working her way through school, Kathy works two part-time jobs for a total of 23 hours a week. Job A pays $5.70 per hour, and Jo
trapecia [35]

Answer:

<u>Kathy worked 11 hours at job A and 12 hours at job B, the week she made US$ 146.70.</u>

Step-by-step explanation:

1. Let's review all the information given for solving this question:

Rate per hour of Job A = US$ 5.70

Rate per hour of Job B = US$ 7.00

Earnings received by Kathy during the week = US$ 146.70

Total time worked by Kathy during the week = 23 hours

Hours at job A = x

Hours at job B = 23 -x

2. Let's find how many hours Katy worked at each job:

This is the equation that we'll use:

5.70x + 7 (23 - x) = 146.70

5.70x + 161 - 7x = 146.70

- 1.3x = 146.70 - 161 (Subtracting 161 at both sides)

-1.3x = - 14.30

1.3x = 14.3 (Multiplying by - 1 at both sides)

x = 14.3/1.3 = 11 (Dividing by 1.3 at both sides)

<u>Kathy worked 11 hours at job A and 12 hours at job B.</u>

3. Proof of x = 11

5.70 x + 7 (23 - x) = 146.70

5.70 (11) + 7 (23 - 11) = 146.70

62.70 + 7 (12) = 146.70

62.70 + 84 = 146.70

146.70 = 146.70

<u>The value of x = 11 is correct.</u>

Note. I provided the same answer to question 13954115.

3 0
2 years ago
Four times a number increased by 3 is -89
sp2606 [1]

Answer:

-21.5

Step-by-step explanation:

4 0
2 years ago
Read 2 more answers
What is the range for
insens350 [35]

Answer:

In statistics, the range of a set of data is the difference between the largest and smallest values.

Step-by-step explanation:

Easy as pie

7 0
2 years ago
Tropical forests are being lost at the rate of 5 million hectares per year. how many hectares per day is that? how many hectares
katrin [286]
5,000,000/365= 13,698.630137 hectatres per day /1440 = 9.5129375951388..... hectares per minute

365 days in a year
1440 minutes in a day (24hrs)


7 0
3 years ago
Livvi invests $19,430 in a savings account at her local bank which pays 1.8% simple annual interest. She also deposits $16,470 i
kogti [31]

Answer:

the answer is B

Step-by-step explanation:

fd

8 0
3 years ago
Read 2 more answers
Other questions:
  • Yolanda is a software saleswoman. Let y represent her total pay (in dollars). Let x represent the number of copies of 'English i
    14·1 answer
  • Can someone help please?? <br><br> I’lginsu edthvukcstghk
    6·1 answer
  • Can Someone Please Help!!!
    11·2 answers
  • Which expression has a value of 24?
    10·2 answers
  • PLEASE HURRY! The price of a wallet is $32.95 and the sales tax is 7.5%. What is the total cost of the wallet?
    13·1 answer
  • Which correctly gives the location of the point (–19, 0)?
    14·2 answers
  • Solve the system of equations below by graphing both equations with a pencil and paper. What is the solution? y = -x + 21 y = -2
    7·1 answer
  • A rock-climbing gym charges nonmembers $18 per
    8·2 answers
  • 7th grade math help me please..
    15·1 answer
  • Can some one please help me
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!