Math 174 Final Exam Solutions - Prof. Li-Tien Cheng, Exams of Mathematics

The solutions to the math 174 final exam held on december 5, 2005. The exam covers topics such as polynomial interpolation, error terms, differential equations, linear systems, and numerical integration. Students are required to show their work to receive credit.

Typology: Exams

Pre 2010

Uploaded on 03/28/2010

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Math 174 Final v1
December 5, 2005
Please put your name, ID number, and sign and date.
There are 8 problems worth a total of 200 points.
You do not need to simplify arithmetic in your answers.
You must show your work to receive credit.
Print Name:
Student ID:
Signature and Date:
Problem Score
1 /25
2 /25
3 /25
4 /25
5 /25
Problem Score
6 /25
7 /25
8 /25
Total /200
1
pf3
pf4
pf5
pf8
pf9

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Math 174 Final v

December 5, 2005

  • Please put your name, ID number, and sign and date.
  • There are 8 problems worth a total of 200 points.
  • You do not need to simplify arithmetic in your answers.
  • You must show your work to receive credit.

Print Name:

Student ID:

Signature and Date:

Problem Score

Problem Score

Total /

  1. (25 pts) Verify that the polynomials

p(x) = x

3

− 5 x

2

  • 13x − 5

q(x) = x

2

  • 2x + 1

interpolate the data

x 1 2 3

y 4 9 16

and explain why this does not violate the unique-

ness of the Lagrange interpolating polynomial.

  1. (25 pts) Suppose f

′ (x) is approximated by the formula φ(h) such that

f

(x) = φ(h) + K 3 h

3

  • K 6 h

6

+....

Use the Richardson extrapolation idea to obtain a formula involving φ(h) and φ(h/2)

with error O(h

6 ).

  1. (25 pts) Solve the system of differential equations

{

x

= y + t

y

′ = x

with initial conditions x(0) = −1 and y(0) = 0 at t = 1/2 using one step of second

order Runge-Kutta,

K

1

= h

F (t,

X)

K

2

= h

F (t + h,

X +

K

1

x(t + h) ≈ x(t) +

K

1

K

2

  1. (25 pts) Let f (x) = 2

x

. Approximate

∫ 4

0

f (x) dx by the trapezoid rule,

∫ b

a

f (x) dx ≈

h

[f (x 0 ) + 2f (x 1 ) +... + 2f (xn− 1 ) + f (xn)],

using partition points 0, 2, and 4. Repeat by using partition points 0, 1, 2, 3, and 4.

Now apply Romberg extrapolation,

R(i, j) = R(i, j − 1) +

j

− 1

[R(i, j − 1) − R(i − 1 , j − 1)],

R(i, 0) = trapezoid rule with 2

i equal subintervals,

to obtain a better approximation.

  1. (25 pts) Calculate an approximate value (as a fraction) for 4

3 / 4 using one step of

Newton’s method,

x n+

= x n

f (x n

f

′ (x n

with x 0