what's wrong in my code?

Answer 1

[Yusuf Suer Erdem]

Hi Alesna, could you try my codes below? Good luck.

clc; clear; close all;

syms y(t) k t
Dy=diff(y);
k=sqrt(2);
ode=diff(y,t,2)==k*sin(k*t);
conds = [y(0)==6, Dy(0)==0];
ySol(t)=dsolve(ode,conds)

[Art dela vega]

it works sir! thank you so much! i've been stuck for this problem for about 3 hours omg. thank you for the help sir. appreciated

[Art dela vega]

sir, just one more question if it is okay. using the code that you gave i tried to answer this question.

[Art dela vega]

[Yusuf Suer Erdem]

Try these codes below. Good luck.

clc; clear; close all;

syms y(x)
Dy = diff(y);

ode = diff(y,x,2) == -5*diff(y,x)-4*y;
cond1 = y(0) == 1;
cond2 = Dy(0) == 0;

conds = [cond1 cond2];
ySol(x) = dsolve(ode,conds);
ySol = simplify(ySol);
ySol(1)

Answer 2

[Walter Roberson]

You created y as a symbolic function, syms y(t)

You try to assign to ySol(y) . But y is a function, and you cannot index by a function.

You could assign to ySol(t)

[Art dela vega]

thank you sir, i found my mistakes on my codes. thank you for the help!