Question
Verify that $\text{y}=4\sin3\text{x}$ is a solution of the differential equation $\frac{\text{d}^2\text{y}}{\text{dx}^2}+9\text{y}=0.$
✓
Answer
We have,
$\text{y}=4\sin3\text{x}\ ...(1)$
Differentiating both sides of equation (1) with respect to 3, we get
$\frac{\text{dy}}{\text{dx}}=12\cos3\text{x}\ ...(2)$
Differentiating both sides of equation (2) with respect to 3, we get
$\frac{\text{d}^2\text{y}}{\text{dx}^2}=-36\sin3\text{x}$
$\Rightarrow\frac{\text{d}^2\text{y}}{\text{dx}^2}=-9(4\sin3\text{x})$
$\Rightarrow\frac{\text{d}^2\text{y}}{\text{dx}^2}=-9\text{y}$
$\Rightarrow\frac{\text{d}^2\text{y}}{\text{dx}^2}+9\text{y}=0$
Hence, the given function is the solution to the given differential equation.
$\text{y}=4\sin3\text{x}\ ...(1)$
Differentiating both sides of equation (1) with respect to 3, we get
$\frac{\text{dy}}{\text{dx}}=12\cos3\text{x}\ ...(2)$
Differentiating both sides of equation (2) with respect to 3, we get
$\frac{\text{d}^2\text{y}}{\text{dx}^2}=-36\sin3\text{x}$
$\Rightarrow\frac{\text{d}^2\text{y}}{\text{dx}^2}=-9(4\sin3\text{x})$
$\Rightarrow\frac{\text{d}^2\text{y}}{\text{dx}^2}=-9\text{y}$
$\Rightarrow\frac{\text{d}^2\text{y}}{\text{dx}^2}+9\text{y}=0$
Hence, the given function is the solution to the given differential equation.
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