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The third, fourth, and fifth terms in the expansion of (x + a)^n are 84, 280, and 560, respectively. Find n. 

 Jan 24, 2019

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When x=2, then:

(2 + a)^7 =x^7 + 14 x^6 + 84 x^5 + 280 x^4 + 560 x^3 + 672 x^2 + 448 x + 128

 Jan 24, 2019
 #1
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Best Answer

When x=2, then:

(2 + a)^7 =x^7 + 14 x^6 + 84 x^5 + 280 x^4 + 560 x^3 + 672 x^2 + 448 x + 128

Guest Jan 24, 2019

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