Find the unique polynomial of degree 4 that takes on values p(1)=2,p(2)=1,p(3)=0,p(4)=4,andp(5)=0. Write your answer in the coefficient representation.

Short Answer

Expert verified

The coefficient representation of unique polynomial equation is:

P0=-20,P1=45.66,P2=-31.25,P3=8.33,P4=-0.75.

Step by step solution

01

Representing generic distinct polynomial

Here is just a representation of the generic distinct polynomial equation with degree "n":

Px=P0+P1x+P1x2+...+Pnxn …… (1)

This following is indeed the equation of a distinct polynomial with degree 4 derived using equation (1):

localid="1659770618378" Px=P0+P1x+P2x2+P3x3+P4x4 …… (2)

Substitute the value of x as “1” in equation (1)

P1=P0+P11+P212+P313+P414=P0+P1+P2+P3+P4…… (3)

Substitute the value of P(1) as “2” in equation (3)

2=P0+P1+P2+P3+P4 …… (4)

Substitute the value of x as “2” in equation (1)

role="math" localid="1659771467014" P2=P0+P12+P222+P323+P424=P0+2P1+4P2+8P3+16P4 …… (5)

Substitute the value of P (2) as “1” in equation (5)

1=P0+2P1+4P2+8P3+16P4 …… (6)

Substitute the value of x as “3” in equation (1)

role="math" localid="1659771489756" P3=P0+P13+P232+P333+P434=P0+3P1+9P2+27P3+81P4 …… (7)

Substitute the value of P(3) as “0” in equation (7)

0=P0+3P1+9P2+27P3+81P4 …… (8)

Substitute the value of as “4” in equation (1)

P4=P0+P14+P242+P343+P444=P0+4P1+16P2+64P3+256P4 …… (9)

Substitute the value of P(4) as “4” in equation (9)

4=P0+4P1+16P2+64P3+256P4 ……(10)

Substitute the value of X as “5” in equation (1)

role="math" localid="1659771676062" P5=P0+P15+P252+P353+P454=P0+5P1+25P2+125P3+625P4 …… (11)

Substitute the value of P(5) as “0” in equation (11)

0=P0+5P1+25P2+125P3+625P4 …… (12)

02

Find determinant of A

Find the coefficients by using cramer’s rule:

The formula for matrix representation is

Ay=B …… (13)

As illustrated in equations (14), equation (15), and equation (16), the equations (4), (6), (8), (10), and (12) may be represented in matrix format as follows:

In matrix A, represent the variables as follows:

localid="1659772894874" A=1111112481613927811416642561525125625(14)

Represent the coefficients localid="1659772510651" P0,P1,P2,P3,P4in matrix y as follows:

Y=P0P1P2P3P4(15)

In matrix B, express those values of both the equation as follows:

B=21040(16)

Substitute equation (14), equation (15) and equation (16) in equation (13).

1111112481613927811416642561525125625×P0P1P2P3P4=21040(17)

Determine that determinant of Either a, and divide each determinant of the coefficient by the determinant of A to find the values of the coefficients P0,P1,P2,P3,P4as follows:

The Gaussian elimination approach may be used to find A's determinant, which is 288.

A=288.....(18)

03

Find coefficients

Next, find the coefficient of P0.

To find the value of P0 , replace the first column of A by B. Thus,

P0=1111112481613927811416642561525125625

The Gaussian elimination approach may be used to find P0's determinant, which is -5760.

P0=-5760..........(19)

Find the coefficient of P0 as,

role="math" localid="1659773416538" Coeff.ofP0=P0A.........(20)

Use equation (18) and equation (19) in equation (20).

role="math" localid="1659773484679" Coeff.ofP0=-5760288Coeff.ofP0=-20...........(21)

Thus, the coefficient of P0 is -20.

Next, find the coefficient of P1 .

To find the value of P1, replace the second column of A by B. Thus,

role="math" localid="1659773613814" P1=1111112481613927811416642561525125625

The Gaussian elimination approach may be used to find P1's determinant, which is 13,152.

P1=13,152.........(22)

Find the coefficient of P1 as,

role="math" localid="1659773738779" Coeff.ofP1=P1A.........(23)

Use equation (18) and equation (22) in equation (23).

role="math" localid="1659773783405" Coeff.ofP1=13,152288Coeff.ofP1=45.66...........(24)

Thus, the coefficient of P1 is 45.66.

Next, find the coefficient of P2.

To find the value of P2, replace the third column of A by B. Thus,

role="math" localid="1659774249002" P2=1111112481613927811416642561525125625

The Gaussian elimination approach may be used to find P2's determinant, which is -9000.

P2=-9000.......(25)

Find the coefficient of P2 as,

role="math" localid="1659774340068" Coeff.ofP2=P2A.........(26)

Use equation (18) and equation (25) in equation (26).

role="math" localid="1659774381998" Coeff.ofP2=-9000288Coeff.ofP2=-31.25.........(27)

Thus, the coefficient of P2 is -31.25.

Next, find the coefficient of P3.

To find the value of P3, replace the fourth column of A by B. Thus,

P3=1111112481613927811416642561525125625

The Gaussian elimination approach may be used to find P3's determinant, which is 2400.

P3=2500.......(28)

Find the coefficient of P3 as,

role="math" localid="1659774519843" Coeff.ofP3=P3A.........(29)

Use equation (18) and equation (28) in equation (29).

role="math" localid="1659774579633" Coeff.ofP3=2400288Coeff.ofP3=8.33.........(30)

Thus, the coefficient of P3 is 8.33.

Similarly, the determinant of the matrix P4 is represented as follows:

P4=-216.....(31)

Substitute coefficient as P4 in equation (18).

Coeff.ofP4=P4A.........(32)

Use equation (18) and equation (31) in equation (32).

Coeff.ofP3=-216288Coeff.ofP2=-0.75.........(33)

Thus, the coefficient of P4 is -0.75.

Therefore, the coefficient representation of unique polynomial equation P0,P1,P2,P3,andP4are-20,45.66,-31.25,8.33and, -0.75.

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