For this case what you should do is:
1) Multiplication of terms within parentheses correctly.
2) Rewrite the expression respecting power properties.
3) Add or subtract terms of equal power.
Note: See attached image.
Answer:
x ^ 3 + 3x ^ 2 -16x - 48 = 0
In this question, you are given the average speed of the car(70miles per hour) and the time of car travel(4.5 hours). The information is enough to find the car travelling distance. The equation would be:
Distance traveled= average speed * duration= 70miles/h * 4.5 h= 315miles
8% = 8 ÷ 100
( 8 ÷ 100 ) × 259 = 20.72
none of the answers in the choices are correct. but if they are, go with letter b because it is closer to 20.72
![T=17.4\sqrt[4]{m}](https://tex.z-dn.net/?f=T%3D17.4%5Csqrt%5B4%5D%7Bm%7D)
Differentiate with respect to time

:

⇒

Plug in

and

:

⇒

≈

sec/month