Geometric vs Arithmetic

What kind of sequence?

400, 200, 100, 50, 25, ...

• Arithmetic

• Geometric

What kind of sequence?

-4, -12, -36, -108,...

• arithmetic

• geometric

What kind of sequence?

• Arithmetic

• Geometric

What kind of sequence?

-4, 12, -36, 108, …

• arithmetic

• geometric

Write the explicit formula for the geometric sequence.

• a_n = 4(3)^n-1

• a_n = 3(4)^n-1

• a_n = -4(3)^n-1

• a_n = 3(-4)^n-1

Write the formula for the geometric sequence.

• a_n = 4(3)^n-1

• a_n = 3(4)^n-1

• a_n = -4(3)^n-1

• a_n = 3(-4)^n-1

Write the formula for the geometric sequence.

• a_n = 4(3)^n-1

• a_n = 3(4)^n-1

• a_n = -4(3)^n-1

• a_n = 3(-4)^n-1

Write the explicit formula for the geometric sequence.

• a_n = 2(100)^n-1

• a_n = 100(2)^n-1

• a_n = 100(1/2)^n-1

• a_n = (1/2)(100)^n-1

Write the explicit formula (u_n) for the geometric sequence.

• a_n = 10(2)^n-1

• a_n = 2(10)^n-1

• a_n = 10(2)ⁿ

• a_n = 2(10)ⁿ

Arithmetic sequences form a linear equation. Geometric sequences form an exponential equation. Given the geometric sequence 2, 6, 18, ..., write an explicit formula.