74.9.6 problem 14

Internal problem ID [16182]
Book : INTRODUCTORY DIFFERENTIAL EQUATIONS. Martha L. Abell, James P. Braselton. Fourth edition 2014. ElScAe. 2014
Section : Chapter 4. Higher Order Equations. Exercises 4.1, page 141
Problem number : 14
Date solved : Tuesday, January 28, 2025 at 08:56:33 AM
CAS classification : [[_2nd_order, _missing_x]]

\begin{align*} y^{\prime \prime }+9 y&=0 \end{align*}

With initial conditions

\begin{align*} y \left (0\right )&=1\\ y^{\prime }\left (0\right )&=-3 \end{align*}

✓ Solution by Maple

Time used: 0.014 (sec). Leaf size: 15

dsolve([diff(y(t),t$2)+9*y(t)=0,y(0) = 1, D(y)(0) = -3],y(t), singsol=all)
 

\[ y = -\sin \left (3 t \right )+\cos \left (3 t \right ) \]

✓ Solution by Mathematica

Time used: 0.013 (sec). Leaf size: 16

DSolve[{D[y[t],{t,2}]+9*y[t]==0,{y[0]==1,Derivative[1][y][0] ==-3}},y[t],t,IncludeSingularSolutions -> True]
 

\[ y(t)\to \cos (3 t)-\sin (3 t) \]