1 e s 1 \cdot 2 \cdot 3 + 2 \cdot 4 \cdot 6 + 3 \cdot 6 \cdot 9 + – InterviewSolution

InterviewSolution

1.

1 e s 1 \cdot 2 \cdot 3 + 2 \cdot 4 \cdot 6 + 3 \cdot 6 \cdot 9 +

Answer»

1.2.3 + 2.4.6 + 3.6.9 +.....+ n.2n.3n

= 1.2.3[ 1^3 + 2^3 +3^3 +4^3+ .... + n^3]

=1.2.3[ (n)(n+1)/2]^2=3/2[(n)(n+1)]^2

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