math (0311) - Series: financial application

three formulas to remember

simple interest:

I = Prn

where:

I = interest
P = principal (original amount)
r = rate per unit
n = number of units

sort of related, learn:

A = P + I

compound interest

An = P ( 1 + r ) ^n

and the reverse..

Vn = P ( 1 - r ) ^n

math (0302) - Series: sum of geometric sequence

contraversial formulas here..

Sn = a (r^n - 1)
........__________
................r - 1

now that's only if r > 1, if r < 1, then you have to switch the 1s and rs around in the formula.

quite the crazy gayness even though it ends up with the same answer.

math (0216) - Series: sigma notation

simple enough to understand. generally the question has that sum sign (sigma) that looks like what would happen if an E and a W had a baby.

underneath it says n = hwatever, and there's a number at the top. and its followed by an equation.

generally.. you sub in whatever numbers come between what n = and the number on the top, into the equation, and then add up the numbers you get.

sigma notation