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Find the term independent of x in the expansion of `(3/2x^2-1/(3x))^6`. |
Answer» `(r+1)^(th)` term in given expression, `T_(r+1) = C(6,r)((3x^2)/2)^(6-r)(-1/(3x))^r` `= C(6,r)(3/2)^(6-r)(-3)^(-r)(x^2)^((6-r)-r)` `T_(r+1)= C(6,r)(3/2)^(6-r)(-3)^(-r)(x)^(12-3r)->(1)` For `T_(r+1)` to be independent of `x`,`(12-3r) = 0` `=>r = 4` So, fifth term of given expression is independent of `x`. `:. T_5 = C(6,4)(3/2)^2(-3)^(-4)` (putting value of r in (1)) ` = 15**9/4**1/81 = 5/12` |
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