The degree of the derivative \( f^{(n)}(x) \) is calculated by differentiating the function \( (x^3 + 2)^{30} \).
Since the original function has a degree of 90, the degree of the derivative of order \( n \) will be \( 70 \).
Hence \( n = 70 \).
If $y = 5 \cos x - 3 \sin x$, prove that $\frac{d^2y}{dx^2} + y = 0$.
Which of the following is an octal number equal to decimal number \((896)_{10}\)?