Geometric formulas

Recursive - Arithmetic

a_n= a_n-1 + d

Recursive - Geometric

a_n = a_n-1 • r

Explicit Rule - Arithmetic

a_n = a₁ + d^(n-1)

Explicit - Geometric

a_n = a₁ + d^(n-1)

Sum of a sequence/ expanding series

Sn = n • (a₁ + a_n) / 2

What terms do you change in the recursive formula for an arithmetic sequence?

d

What term do you substitute in the recursive formula of a geometric sequence?

r

in an explicit rule, what terms are changed in an arithmetic sequence?

a₁ and d

in an explicit rule, what terms are changed in a geometric sequence?

a₁ and r

when finding the sum of a sequence, what terms in the formula are substituted?

n, a₁ and a_n

slope-intercept

y=mx+b

point slope - one point

y-y₁=m (x-x₁)

formula to find slope of TWO POINTS

y₂-y₁ / x₂-x₁

how to find both y AND x intercepts

set one variable equal to zero and solve for the other

WORD PROBLEM - “per” refers to what variable

m (or slope)

WORD PROBLEM - the initial or starting amount in the problem refers to what variable

b