2
sum(a+bi | i < n) = 2((n(a+a+b(n-1))) 
2)
i | i < n)2 = n(a+a+b(n-1))
sum(a+bi | i < n) = ((n(a+a+b(n-1))) 2)
a,b:, n:
. na = nb 
a = b)
| 1 | 2sum(a+bi | i < n) = 2((n(a+a+b(n-1))) 2) | 6 steps |
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