If (1 + ax)n = 1 + 8x + 24x2 + .... then a × n is: - Vidyadip

MCQ

If (1 + ax)ⁿ = 1 + 8x + 24x² + .... then a × n is:

A
8
B
12
C
16
D
24

✓

Answer

8

Solution:

(1 + ax)ⁿ= 1 + 8x + 24x² + ..........

⇒ ⁿC₀ + ⁿC₁(ax) + ⁿC₂.(ax)² + ...... = 1 + 8x + 24ax² ..........

⇒ 1 + (na)x + ⁿC₂.(ax)² + ...... = 1 + 8x + 24ax² ..........

Comparing coefficient of x in R.H.S to that in L.H.S.Thus n × a = 8

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