Series Formulas / Scope

[webmanik]

Are these formulae useful on the test ? I want to make sure, that i'm not overlooking some basic foundations in GMAT math, which would preclude me from using these formulae on arithmetic progressions.

Term n of a series given first term, An = A1 + (n-1)d
Term n of a series given m'th term, An = Am + (n-m)d

Sum of n terms = (A1+ An) / 2
or = (2A1 + (n-1)d) / 2

[jnelson0612]

Most definitely! These are good formulas to know.