HELP PLS Find the formula for the nth term of the sequence below.

20, −10, 5, −2.5, ...

a)an=−12⋅20nA sub n is equal to negative 1 half times 20 to the n th power

b)an=−12⋅20n−1A sub n is equal to negative 1 half times 20 raised to the n minus 1 power

c)an=20⋅(−12)nA sub n is equal to 20 times open paren negative 1 half close paren to the n th power

d)an=20⋅(−12)n−1

4a. is 3 miles every hour

4b. is 1/3 of an hour per mile

step-by-step explanation:

d. $180

step-by-step explanation:

if the dimensions of the room is 9ft by 12 ft, we have the area of the floor as,

so the area of the floor is 108 square feet, converting that into square yards we get,

the cost of carpet is $15 per square yard, therefore the cost of carpet for 12 square yards is,

hence, the cost of carpet is $180.

assuming the dimensions of the room be,

15 ft by 12 ft

so, the area of the floor of that room is,

we can convert 180 square feet into square yards, we know that,

1 sq ft = 0.111 sq yard

so, 180 square feet is,

so the area of floor is 20 square yards.

now, the cost of carpet is 15 dollars per square yard, therefore the cost of carpet for 20 square yards is,

so, it will cost $300.

can you take a photo of the screen?

your answer is

a.

5

step-by-step explanation: