2.1857   ODE No. 1857

1. Problem in Latex
2. Mathematica input
3. Maple input

$$\{x^{\prime }(t)=ay(t),y^{\prime }(t)=-ax(t)\}$$ ✓ Mathematica : cpu = 0.0358411 (sec), leaf count = 39

$$\left\{\{x(t)\to c_2\sin (at)+c_1\cos (at),y(t)\to c_2\cos (at)-c_1\sin (at)\}\right\}$$

✓ Maple : cpu = 0.045 (sec), leaf count = 35

$$\left\{\{x\left(t\right)=\mathit{\_}\mathit{C}\mathit{1}\sin \left(at\right)+\mathit{\_}\mathit{C}\mathit{2}\cos \left(at\right),y\left(t\right)=\cos \left(at\right)\mathit{\_}\mathit{C}\mathit{1}-\sin \left(at\right)\mathit{\_}\mathit{C}\mathit{2}\}\right\}$$