Answer:
C) p(x) has a zero between x=2 and x=4
Step-by-step explanation:
For a polynomial p(x), means that, when p(x) is divided by
, the remainder is
.
This is called the remainder theorem
Therefore ,
means that when p(x) is divided
and
is 1 and
respectively.
Also the Intermediate value theorem says that, if p(a) and p(b) have opposite signs then there is a certain on
where
i.e there is a zero between
and
Therefore the correct answer is C
The cost of the least expensive fence is $3200
Step-by-step explanation:
The given is:
We need to find the cost of the least expensive fence
Assume that the length of each side opposite to North or South is x feet and the length of each other sides is y feet
∵ The length of the rectangle = x feet
∵ The width of the rectangle = y feet
∵ The rectangular area is 20,000 ft²
- Area of a rectangle = length × width
∴ x × y = 20,000
- Divide both sides by x to find y in terms of x
∴
The fence's length is equal to the perimeter of the rectangular area
∵ Perimeter of the rectangle = 2 length + 2 width
∴ Perimeter of the rectangle = 2x + 2y
∵ Fencing material costs $4 per foot for the two sides facing
North and South
∴ x costs $4 per foot
∵ The cost of the other two sides is $8 per foot
∴ y costs $8 per feet
The cost of the fence is the sum of the products of 4 , 2x and 8 , 2y
∵ The cost of the fence (C) = 4(2x) + 8(2y)
∴ C = 8x + 16y
- Substitute y by its value above
∴
∴
To find the least expensive differentiate C with respect to x and equate the answer by 0 to find the value of x
∵ can be written as
∴
∵
∴
- Equate by zero
∴
∵
∴
- Subtract 8 from both sides
∴
- Multiply both sides by x²
∴ - 320,000 = - 8x²
- Divide both sides by -8
∴ 40,000 = x²
- Take √ for both sides
∴ 200 = x
Substitute x in the equation of C to find the least cost of fence
∵
∴ C = 1600 + 1600
∴ C = 3200
The cost of the least expensive fence is $3200
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