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Mathematics 18 Online
mikewwe13:

https://static.k12.com/nextgen_media/assets/8078625-NG_AL1_J_03_U06_Quiz_15.png The graph shows the maximum height, in inches, reached by a pendulum on each swing. On what swing did the pendulum's maximum height dip below 1 in. for the first time? A. the 3rd swing B. the 4th swing C. the 5th swing D. the 6th swing

mikewwe13:

@Vocaloid

Vocaloid:

select the first x-coordinate where the matching y-coordinate is less than 1

mikewwe13:

C

Vocaloid:

you're getting closer but there's one x-coordinate less than 5 that has as y-coordinate less than 1

mikewwe13:

ok i worked it out it's either B or D because A is out of the question and C

mikewwe13:

so since i checked the graph, it's D

Vocaloid:

|dw:1511976606639:dw|

Vocaloid:

|dw:1511976611849:dw|

mikewwe13:

oh B

Vocaloid:

good

mikewwe13:

https://static.k12.com/nextgen_media/assets/8078569-NG_AL1_J_03_U06_Quiz_01.png The graph shows a car's value as a function of its age. Select from the drop-down menus to correctly describe the graph. The graph shows exponential __________. decay or growth As the value of the car decreases, time ____________. increases or decreases

Vocaloid:

is the value of the car going up or down as the age increases?

mikewwe13:

UP

Vocaloid:

|dw:1511976835055:dw|

mikewwe13:

no down

Vocaloid:

|dw:1511976840214:dw|

Vocaloid:

good so it should be decay and decreases

mikewwe13:

https://static.k12.com/nextgen_media/assets/8078622-NG_AL1_J_03_U06_Quiz_06.png The points on the curve represent the number of teams remaining in a tournament as a function of the number of games that have been played. What is the number of teams who began the tournament? Enter your answer in the box. __________

Vocaloid:

hint: what is the number of teams when games played = 0

mikewwe13:

8

Vocaloid:

remember that games played is on the x-axis |dw:1511977000394:dw|

Vocaloid:

|dw:1511977008852:dw|

mikewwe13:

4

Vocaloid:

each coordinate is (games played, teams remaining) so what is the y-value when x = 0?

mikewwe13:

4

Vocaloid:

|dw:1511977132086:dw|

mikewwe13:

64

Vocaloid:

good, (0,64) means 64 games at the start so 64 = your answer

mikewwe13:

https://static.k12.com/nextgen_media/assets/8078571-NG_AL1_J_03_U06_Quiz_07.png The graph shows the processing speeds of computers as a function of time since 1980. Which statements are true about the function? Select each correct answer. The practical domain is x > 0 , so the processing speed increases over time. The graph is ascending, indicating that the processing speed increases over time. The practical range is y ≥ 16 , so the processing speeds are always positive. The point (0, 16) represents an initial processing speed of 16 MHz. The point (10, 256) represents the maximum processing speed.

Vocaloid:

well first off is the graph increasing or decreasing?

mikewwe13:

decreasing

Vocaloid:

|dw:1511977304644:dw|

Vocaloid:

|dw:1511977309868:dw|

mikewwe13:

increasing

Vocaloid:

good since 0 is included in the domain, statement 1 is actually false since x > 0 excludes 0 from the domain

Vocaloid:

statement 2 we said was true (increasing graph)

Vocaloid:

for statement 3, the minimum y-value is 16 so statement 3 is true

mikewwe13:

1st one right and 2

mikewwe13:

wrong

Vocaloid:

statement 4 is true since this represents the speed when x = 0

Vocaloid:

statement 5 is false because the graph has no maximum (notice how the graph increases past (10,216)

mikewwe13:

https://static.k12.com/nextgen_media/assets/8078624-NG_AL1_J_03_U06_Quiz_12.png After being dropped from a platform, a ball bounces several times. The graph shows the height of the ball after each bounce. What does the end behavior for x increasing without bound represent? A. The height of the platform is unknown. B. The ball will never stop bouncing. C. The end behavior for x decreasing without bound is meaningless in this situation. D. The height of each bounce will approach 0 m.

Vocaloid:

as a hint, notice how the height gets closer and closer to 0 as the # of bounces increase

Vocaloid:

which answer choice matches this statement?

mikewwe13:

B

Vocaloid:

key phrase: "height gets closer to 0"

mikewwe13:

D

Vocaloid:

good, d

mikewwe13:

What is the recursive rule for an = 4n − 1? A. a1 = 4;an = an−1 − 1 B. a1 = 3; an = an−1+ 4 C. a1= −1; an = an− 1 + 4 D. a1 = 3; an = an −1 −1

Vocaloid:

first step is to calculate a1 using n = 1 when n = 1, what does 4n - 1 equal?

mikewwe13:

3

Vocaloid:

good, now calculate 4n - 1 when n = 2

mikewwe13:

7

Vocaloid:

good, and if you continue this pattern, the term increases by 4 each time making B the only answer that matches the initial term and rate of change

mikewwe13:

Haylee opened her savings account with $440 in Week 1. Each week after this, she deposited $65 in her account. How much money will Haylee have in her savings account after Week 25? Enter your answer in the box. $__________

Vocaloid:

general formula for sequences an = a1 + (n-1)d a1 = first term d = common difference n = number of terms

Vocaloid:

in this case, 440 is the first term, d is the rate of increase (65)

Vocaloid:

so our formula becomes an = 440 + (n-1)*65 let n = 25 and find an

mikewwe13:

5 • (13n + 75)

Vocaloid:

440 + (n-1)*65 replace "n" with "25" and calculate this

mikewwe13:

2000

Vocaloid:

good that's it.

mikewwe13:

What is the 8th term in the sequence? an = 25 − 3n Enter your answer in the box. ___________

mikewwe13:

my answer is 1

Vocaloid:

good that's it.

mikewwe13:

What is the explicit rule for the sequence? 15.5,13,10.5,8,5.5,3,... A. an=18 − 2.5n B. an=15.5 + 2.5n C. an=15.5 − 2.5n D. an=18 + 2.5n

mikewwe13:

MY ANSWER IS A

Vocaloid:

nvm that's right

mikewwe13:

What is the common difference, d, of the sequence? −92, −74, −56, −38, −20, ... Enter your answer in the box. d = _____

mikewwe13:

my answer is 18

Vocaloid:

good

mikewwe13:

What is the value of a3 in the sequence? 2,5,10,17,... A. 2 B. 5 C. 10 D. 17

mikewwe13:

MY ANSWER IS D

Vocaloid:

a3 means the third term

Vocaloid:

counting from the left, the third term is 10

mikewwe13:

really are you sure?

mikewwe13:

Which answer describes the type of sequence? 99,89.9,78.8,68.7,... A. geometric B. neither arithmetic nor geometric C. arithmetic

mikewwe13:

my answer is B

Vocaloid:

good.

mikewwe13:

Which answer describes the type of sequence? 1,6,7,13,... A. arithmetic B. neither arithmetic nor geometric C. geometric

Vocaloid:

is there a common difference or a common ratio?

mikewwe13:

common ratio

Vocaloid:

is 13/7 equal to 7/6?

mikewwe13:

no

Vocaloid:

good so there must be no common ratio making the sequence not geometric and not arithmetic

Vocaloid:

so B

mikewwe13:

Which answer describes the type of sequence? 3,4,5,6,... A. arithmetic B. neither arithmetic nor geometric C. geometric

Vocaloid:

is there a common difference or ratio?

mikewwe13:

common difference

Vocaloid:

good so arithmetic (A)

mikewwe13:

What is the value of a1 in the sequence? −4,−2,− 1/2,− 1/4,... A. ​ −1/4 B. ​ −1/2 ​ C. −4 D. ​ −2 ​

Vocaloid:

what's the first number in the sequence?

mikewwe13:

C

Vocaloid:

good

mikewwe13:

What is the explicit rule for this geometric sequence? 2/9, 2/3, 2, 6,... A. an = 3(2/9)^n B. an = 3(29)^n−1 C. an = 2/9 ⋅ 3^n D. an = 2/9 ⋅ 3^n−1

Vocaloid:

|dw:1511979407260:dw|

Vocaloid:

in this case your first term is (2/9) and the common ratio is 3

Vocaloid:

substitute these values into the formula and pick the answer that matches

mikewwe13:

the answer is B and C

Vocaloid:

there is only one correct answer

Vocaloid:

|dw:1511979564396:dw|

Vocaloid:

a = (2/9) and r = 3 which answer choice matches the correct formula?

mikewwe13:

D

Vocaloid:

good.

mikewwe13:

What is the recursive rule for this geometric sequence? 3, 3/2, 3/4, 3/8,... A. a1 = 3; an =1/2 ⋅ an−1 B. a1 = 3/2;an = 1/2 ⋅ an−1 C. a1 = 1/2; an = 3/2 ⋅ an−1 D. a1 = 1/2; an = 3 ⋅ an−1

Vocaloid:

the first term (a1) is 3 so there is only one answer choice that matches

mikewwe13:

A

Vocaloid:

good

mikewwe13:

What is the explicit rule for this geometric sequence? a1 = 4; an = 1/3 ⋅ an−1 A. an = 1/3 ⋅ 4n B. an = 1/3 ⋅ 4n−1 C. an = 4(1/3)n−1 D. an = 4(1/3)n

Vocaloid:

first term is 4, common ratio is (1/3) so using the formula from earlier find the explicit formula

Vocaloid:

|dw:1511980010410:dw|

mikewwe13:

B

Vocaloid:

hint: the common ratio is the part that gets raised to the n - 1power

Vocaloid:

the first term is on the left of the formula

mikewwe13:

D

Vocaloid:

the exponent is n - 1 not just n

mikewwe13:

c

Vocaloid:

good, c.

Vocaloid:

use the geometric formula where first term = 100 and common ratio = 11/2, for n = 5

mikewwe13:

A company earns a profit of $100 the first month it is in business. Every month after that, the company earns a profit that is 1 1/2 times the previous month's profit. What will the company's profit be in the fifth month?

mikewwe13:

sorry typ

mikewwe13:

my answer is $506.25

Vocaloid:

good.

mikewwe13:

What is the common ratio for the geometric sequence? 54,36,24,16... Enter your answer in the box. ___________

Vocaloid:

just divide the 2nd term by the first term

Vocaloid:

36/54 and reduce to the lowest terms

mikewwe13:

2 — = 0.66667 3

Vocaloid:

good, if you can enter it as 2/3 I would recommend that otherwise I guess you could round to 0.6667 or whatever

mikewwe13:

the answer is 3/2

mikewwe13:

correct ?

Vocaloid:

it is 2/3

mikewwe13:

What is the recursive rule for this geometric sequence? 7, 21, 63, 189, … A. a1 = 7; an = 3 ⋅ an−1 B. a1 = 3; an = 7 ⋅ an−1 C. a1 = 7;an = 1/3 ⋅ an−1 D. a1 = 21;an= 7 ⋅ an−1

Vocaloid:

hint - what's the common ratio? what's the first term?

mikewwe13:

7

Vocaloid:

good, first term is 7 and what is the common ratio?

mikewwe13:

21

Vocaloid:

to find the common ratio divide the 2nd term by the 1st term

Vocaloid:

21/7 = ?

mikewwe13:

3

mikewwe13:

3

mikewwe13:

3

Vocaloid:

good, so pick the answer choice where a1 = first term = 7 and an = common ratio * a^(n-1)

mikewwe13:

D

Vocaloid:

a1 must be 7 not 21.

mikewwe13:

C

Vocaloid:

the common ratio is 3 not 1/3

mikewwe13:

A

Vocaloid:

good.

Vocaloid:

can we close this and open a new question, it's getting laggy

mikewwe13:

YES

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