What is the third term in the expansion of (x + 2)6?
Solution:
Given (x + 2)6
We use binomial theorem to get the expansion
(a + b)n = ∑(k = 0 to n) nCk (an - k × bk)
Here, a = x and b = 2, n = 6
(x + 2)6 = ∑(k=0 to n) 6Ck (x)6 - k × (2)k
(x + 2)6 = 6! /6!0! (x)6(2)0 + 6!/(6 - 1)!1! (x)5(2)1 + 6!/(6 - 2)!2! (x)4(2)2 + 6!/(6 - 3)!3! (x)3(2)3 + 6!/(6 - 4)!4! (x)2(2)4 + 6!/(6 - 5)!5! (x)1(2)5
(x + 2)6 = 1 × (x)6(2)0 + 6 × (x)5(2)1 + 15 × x4(2)2 + 20x3(2)3 + 15 × x2(2)4 + 6x1(2)5 + 1 × x0(2)6
(x + 2)6 = x6 + 12x5 + 60x4 + 160x3 + 240x2 + 192x + 64
Coefficient of the third term is 60
What is the third term in the expansion of (x + 2)6?
Summary:
The third term in the expansion of (x + 2)6 is 60.
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