Alg 2 Unit 8 Lesson 2: Arith & Geom Sequences - Formulas

Alg 2 Unit 8 Lesson 2: Arith & Geom Sequences - Formulas

Looks like this car's license plate may be a formula for disaster...

Let's learn more about formulas!!!

Multiple Choice

 What is the sum of the first 20 terms of the arithmetic sequence?$\frac{1}{3},\ \frac{2}{3},\ 1,\ \frac{4}{3},\ \frac{5}{3},\ ...$  

• 5

• 20

• 70

• 140

Multiple Choice

What does the 'S' mean in the formula sheets listed by the Commonwealth of Virginia?

• Sequence (Find a specific number in the sequence)

• Simplify (Combine using PEMDAS)

• Summation Notation (Denoted by a capital Greek sigma)

• Series (Add a set number of terms together)

Multiple Choice

Find the explicit formula:
-3, -33, -63, -93, ...

• a_n = -3 - 30(n -1)
• a_n = -3 + 30(n -1)
• a_n = -30 - 3(n -1)
• a_n = -30 + 3(n -1)

Multiple Choice

Find the explicit formula:
-23, -16, -9, -2, ...

• a_n = -23 + 7(n -1)
• a_n = -23 - 7(n -1)
• a_n = 7 - 23(n -1)
• a_n = 7 + 23(n -1)

Multiple Choice

 $2,\ 10,\ 50,\ 250,\ ...$  Find the explicit formula

•  $a_n=10\cdot4^{\left(n-1\right)}$  

•  $a_n=2\cdot5^{\left(n-1\right)}$  

•  $a_n=10\cdot5^{\left(n-1\right)}$  

•  $a_n=5\cdot2^{\left(n-1\right)}$  

Multiple Choice

 $-2,\ -4,\ -8,\ -16,\ ...$  Find the explicit formula

•  $a_n=2\cdot5^{\left(n-1\right)}$  

•  $a_n=2\cdot\left(-2\right)^{\left(n-1\right)}$  

•  $a_n=-2\cdot2^{\left(n-1\right)}$  

•  $a_n=2\cdot2^{\left(n-1\right)}$  

Multiple Choice

Evaluate the geometric series $1-2+4-8,\ ...,\ \ \ \ \ \ \ n=8$  

•  $\frac{1}{3}$  

• -86

• -87

• -85