multiplying polynomials with conv

use matlab to carry out the following multiplication of polynomials

(x+1.4)(x-0.4)x(x+0.6)(x-1.4)

heres what i did---

a = [1,1.4];
b = [1, -.4];
c = [1, 0];
d = [1, .6];
e = [1, -1.4];
p = conv(a, conv(b, conv(c, conv(d, e))))

it gave me the correct result but its tagging an extra zero onto the end of my result. i assume this means its coming out as one higher power then it is supposed to be with a "0" constant. anyone see any problems here?

my answer is supposed to come out as

p = [1, 0.2, -2.2, -3.92, .4704]

while my work is giving me

p = [1, 0.2, -2.2, -3.92, .4704, 0]

so somewhere it is giving me an extra power of x and im not sure why

[Valeriy Fedorikhin]

Your answer is correct. There is a typo in the book - don't worry about it.

Answer 1

[Fangjun Jiang]

That is because you have one term as x, right? So the result will not have the constant term, as you specify [1,0] for x.

[Morley]

my answer is supposed to come out as

p = [1, 0.2, -2.2, -3.92, .4704]

while my work is giving me

p = [1, 0.2, -2.2, -3.92, .4704, 0]

so somewhere it is giving me an extra power of x and im not sure why

[Fangjun Jiang]

No! The p given by conv() is correct. Double check your formula. The x in the middle, do you mean x or *?

[Morley]

yes that is just an x

ok maybe my answer is coming out correct

now i need to plot

Answer 2

[Iqra]

Question

use MATLAB to carry out the following multiplication of polynomial x(x 1.8)(x-0.4)(x-1.6) plot the polynomial in the domain "-2<=x<=2."

ANSWER

% Define the polynomials
P = [1 18 0]; % x(x + 18)
Q = [1 -2 -0.64]; % (x - 0.4)(x - 1.6)

% Multiply the polynomials
result = conv(P, Q);

% Plot the polynomial
fplot(@(x) polyval(result, x), [-2, 2]);
title('Plot of the Polynomial');
xlabel('x');
ylabel('P(x) * Q(x)');
grid on;

[DGM]

Please format your answers. It's easier to read, and formatted code can be run right here on the forum, directly demonstrating the results.