Answer:
Sum is - 5n² -8n + 4.
Step-by-step explanation:
Given : (3n² – 5n + 6) + (–8n²– 3n – 2) .
To find : Sum .
Solution : We have (3n² – 5n + 6) + (–8n²– 3n – 2) .
Combine like terms :
(3n² - 8n²– 5n - 3n + 6 - 2).
- 5n² -8n + 4.
Therefore, Sum is - 5n² -8n + 4.
Answer:
The area of a horizontal cross section at a height is 
Step-by-step explanation:
Given that,
Height = 14 m
Radius = 2 m
Let V be the volume of a right circular cone
We need to calculate the value of R
Using given data

Put the value into the formula



We need to calculate the area of a horizontal cross section at a height y
Using formula of area

Put the value into the formula

Hence, The area of a horizontal cross section at a height is 
Answer:
C. 0.3682
Step-by-step explanation:
a repeating decimal goes on forever
Yes.
30 x .30 = 9 cm is a 30% decrease
30-9= 21 cm