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What is the value of $14^{3} + 16^{3} + 18^ 3 + ... + 30^{3}$ ?
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$14^3 + 16^3 + 18^3 +....+ 30^3 $
$=8(7^3 + 8^3 + 9^3 +....+ 15^3)$
Sum of n cubes $=(n(n+1)/2)^2$
for $n=6$ we have $21^2=441$ for $n=15$ we have $120^2=14400$ Difference$=14400-441 =13959$
$=8(7^3 + 8^3 + 9^3 +....+ 15^3)$
Sum of n cubes $=(n(n+1)/2)^2$
for $n=6$ we have $21^2=441$ for $n=15$ we have $120^2=14400$ Difference$=14400-441 =13959$