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: get a conversion sheet out i dont know the exact measurments

step-by-step explanation: divide the number of feet with the nu,ber of milrs and there your answer