Polynomial evaluation and roots in MATLAB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to evaluate the polynomial p at x = 2.

MATLAB

p = [1 -3 2];
y = polyval(p, [1]);

Drag options to blanks, or click blank then click option'

A2

B3

Cx

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable name instead of a number.

Forgetting to pass the evaluation point as the second argument.

The function polyval evaluates the polynomial p at the given value. Here, we want to evaluate at 2.

2fill in blank

medium

Complete the code to find the roots of the polynomial p.

MATLAB

p = [1 -3 2];
r = [1](p);

Drag options to blanks, or click blank then click option'

Apolyval

Broots

Csolve

Dfind

Attempts:

3 left

💡 Hint

Common Mistakes

Using polyval instead of roots.

Using find which is for arrays, not polynomials.

The roots function returns the roots of the polynomial defined by the vector p.

3fill in blank

hard

Fix the error in the code to correctly evaluate the polynomial p at x = 5.

MATLAB

p = [2 0 -1 3];
y = polyval([1], 5);

Drag options to blanks, or click blank then click option'

Ap

Bpolyval

C[2 0 -1 3]

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the arguments of polyval.

Passing the number as the first argument.

The first argument to polyval must be the polynomial coefficients vector p, not the evaluation point.

4fill in blank

hard

Fill both blanks to create a polynomial vector for p(x) = 3x^2 - 4x + 1 and evaluate it at x = 3.

MATLAB

p = [[1] [2] 1];
y = polyval(p, 3);

Drag options to blanks, or click blank then click option'

A3

B-4

C4

D-3

Attempts:

3 left

💡 Hint

Common Mistakes

Using positive 4 instead of -4.

Swapping the order of coefficients.

The polynomial coefficients are in descending powers: 3 for x^2, -4 for x, and 1 constant.

5fill in blank

hard

Fill all three blanks to create a polynomial vector for p(x) = x^3 - 6x^2 + 11x - 6 and find its roots.

MATLAB

p = [[1] [2] [3] -6];
r = roots(p);

Drag options to blanks, or click blank then click option'

A1

B-6

C11

D6

Attempts:

3 left

💡 Hint

Common Mistakes

Using positive 6 instead of -6.

Mixing up the order of coefficients.

The polynomial coefficients are for x^3, x^2, and x terms respectively: 1, -6, and 11.