If a curve \( y = f(x) \) passes through the point \( (1, 2) \) and satisfies \( x \, \frac{dy}{dx} + y = b x^4 \), then for what value of \( b \), \( \int\limits_{1}^{2} f(x) \, dx = \frac{62}{5} \)?
\( \frac{62}{5} \)
\( \frac{31}{5} \)
\( 5 \)
\( 10 \)