If the rth term in the expansion of { x/3 - 2/x^2}^10 contains x^4, then r is equal to

Question

If the rth term in the expansion of \(\big(\frac{x}{3} - \frac{2}{x^2}\big)^{10}\)contains x⁴, then r is equal to

(a) 3 

(b) 0 

(c) – 3 

(d) 5

Answer 1

Answer : (a) 3

General Term = T_r+1 = ⁿC_r (x) ^n–r (a)^r in the expansion of (x + a) ^n.