Question

The order and degree of the differential equation $\sqrt[3]{3\frac{dy}{dx}}-4\frac{d^{2}y}{d{x}^2}-7x=0$ are a and b, then a + b is:

• A. 3
• B. 4
• C. 5
• D. 6

Answer 1

The correct option is C 5

$\sqrt[3]{3\frac{dy}{dx}}-4\frac{d^{2}y}{d{x}^2}-7x=0\Rightarrow \sqrt[3]{3\frac{dy}{dx}}=7x+4\frac{d^{2}y}{d{x}^2}\Rightarrow \frac{dy}{dx}={(7x+4\frac{d^{2}y}{d{x}^2})}^3$
Hence order is $2$ and degree is $3$
Therefore $a+b=2+3=5$