Geometric Sequence and Series

Find the sum of the infinite geometric series, if it exists:
200 - 100 + 50 - 25 +

• Does not exist

• 400/ 3

• 3 / 400

Write an explicit rule for the general term of the sequence 5, 15, 45, . . . ?

• a_n = a_n-1 x 3

• a_n = 5(3)^n-1

• a_n = 3(5)^n-1

• a_n = 5 + (n-1)3

What is the twelfth term in the sequence 3, -6, 12, . . . ?

• -2,048

• 6,144

• -6,144

• -531,441

                    a₁
S_n =     ------------------
                   1 - r
What formula is this?

• Infinite Arithmetic Series Formula

• Finite Geometric Series Formula

• Finite Arithmetic Series Formula

• Infinite Geometric Series Formula

Find the sum, if possible

• -4/3

• 4/15

• 1

• not possible

Find the next three terms: 3, -18, 108, -648

• -6480, -3880, -233280

• 6480, -38880, 233280

• 5184, -31104, 186624

• 3888, -23328, 139968

What is the sum of the first ten terms of the sequence 4, -12, 36, -108 . . . ?

• 59,050

• -59,048

• -78,732

• 118,096

Find the indicated sum for the geometric series.
S₆ for (-4/5) + 8 + (-80) + 800 + ....

• _S6 = 21,845

• _S6 = 72,000

• _S6 = 72,727.2

• _S6 = -128,840.8

Is the sequence 2, 4, 12, 48,... geometric?

• yes

• no

What is the explicit rule for the sequence:
11, 22, 44, 88...

• _gn = 2(11)^n-1

• _gn = 11x2

• _gn = 11(2)^n-1

• g_n = 11+(2)^n-1