Math Is Fun Forum

[math] Part (a): Find the sum
a + (a + 1) + (a + 2) + ... + (a + n - 1)
in terms of a and n.                                               

Part (b): Find all pairs of positive integers (a,n) such that n \ge 2 and
a + (a + 1) + (a + 2) + ... + (a + n - 1) = 100.

note: \ge=greater than or equal to.