The function C(x) = -2x2 + 38x + 40 models the sales, in hundreds of millions of dollars, of compact discs for years since 1990.

Question:

Rewrite the function to reveal when sales of compact discs and $0.

The cost in 2010 is $0

Step-by-step explanation:

Given

Required

Find x when

This gives:

Expand

Factorize:

Solve for x

x represents time.  So, it cannot be negative.

20 years after 1990 is: 2010. Hence, the cost in 2010 is $0

answer: 323 is how many she has ☃☃⛄❄

step-by-step explanation:

45.36 feet per second

step-by-step explanation:

tyrone travels 30 miles in 58.2 minutes.  

1 mile = 5280 feet; this means he travels

30(5280) = 158400 feet in 58.2 minutes.

1 minute = 60 seconds; this means he travels 158400 feet in

58.2(60) = 3492 seconds.

this gives us the unit rate of

158400/3492 = 45.36 feet per second.