Benjamin writes an expression for the sum of 1 cubed, 2 cubed and 3 cubed. What is the value of the expression?
1 answer:
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You could rewrite 
as
and be tempted to cancel out the factors of
. But this cancellation is only valid when 
.
When
, you end up with the indeterminate form 
, which is why 
is not a zero.
and be tempted to cancel out the factors of
When
