If the coefficient of \( x^7 \) in \( \left(x^2 + \dfrac{1}{bx}\right)^{11} \) and \( x^{-7} \) in \( \left(x - \dfrac{1}{bx^2}\right)^{11} \), \( b \neq 0 \), are equal, then the value of \( b \) is equal to:
\( -1 \)
\( 1 \)
\( 2 \)
\( -2 \)
