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Question
The constant term in the expansion of `(x + 2/x)^6` is
Options
156
165
162
160
Solution
160
Explanation:
Here x is x, a is `2/x`
∴ Constant term occurs only in middle term n = 6
∴ middle term = `"t"_(6/2+1) = "t"_(3+1)`
`"t"_(3+1) = 6"C"_3 (x)^3 (2/x)^3`
`= (6 * 5 * 4)/(3 * 2 * 1) x^3 xx 2^3/x^3 = 20 xx 8 = 160`
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