Find the term independent of x in the expansion of \( (\dfrac{3}{2x^2} – \dfrac{1}{3x})^9\)

Find the middle term in the expansion of \((x-\dfrac{ 1}{x})^{2n+1}\)

Find the middle term in the expansion of (1 + 3x + 3x^{2} + x^{3})^{2n}

Find the middle term in the expansion of (1 – 2x + x^{2})^{n}

Find the middle term in the expansion of \( (\dfrac{x}{a} – \dfrac{a}{x})^{10}\)