0 = 1

Calculus Level 4

$\begin{array} { l l r } 0 & = ( 1 -1 ) & \text{ Step 1 } \\\\ & = ( 1 -1 ) + ( 1 - 1) & \text{ Step 2 } \\\\ & = ( 1 -1 ) + ( 1 - 1) + (1-1) + (1-1) + \cdots & \text{ Step 3 } \\\\ & = 1 -1 + 1 - 1 + 1 - 1 + 1 - 1 + \cdots & \text{ Step 4 } \\\\ & = 1 + (-1 + 1) + (- 1 + 1) + (-1+1) + \cdots & \text{ Step 5 } \\\\ & = 1 & \text{ Step 6 } \end{array}$

In which step above did we first introduce an error?

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