Jane and Jill want their mom to ride the roller coaster with them, but she thinks it will be too fast. She asks the girls to find out how fast the roller coaster will be traveling. They find out that the speed of the roller coaster, in miles per hour, is modeled by the function g(x) = x4 − 4x2 + 7x − 8, where x is time measured in seconds. How fast is the roller coaster traveling at 2 seconds?

6 miles per hour
22 miles per hour
26 miles per hour
54 miles per hour

1 answer

To find out how fast the roller coaster is traveling at 2 seconds, we need to evaluate the given function \( g(x) = x^4 - 4x^2 + 7x - 8 \) at \( x = 2 \).

Substituting \( x = 2 \) into the function:

\[ g(2) = (2)^4 - 4(2)^2 + 7(2) - 8 \]

Now, calculate each term separately:

\[ (2)^4 = 16 \]
\[ 4(2)^2 = 4 \cdot 4 = 16 \]
\[ 7(2) = 14 \]
\[ -8 \]

Combine these values:

\[ g(2) = 16 - 16 + 14 - 8 \]

Perform the addition and subtraction:

\[ g(2) = 16 - 16 = 0 \]
\[ 0 + 14 = 14 \]
\[ 14 - 8 = 6 \]

So, the roller coaster is traveling at 6 miles per hour at 2 seconds.

Therefore, the correct answer is:
6 miles per hour