Answer:
Step-by-step explanation:
First we need to find area of the triangle with a base of 4 cm and a height of 5cm, and then multiply that by the length of the prism of 15cm.
The area of the triangle is given by the formula:
where b is the base: and h is the height:
thus, in this case we have:
And now, the volume will be the area of the triangle multiplied by the length of the prism:
Substituting the known values:
The volume in cubic centimeters is 150.
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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Answer:
b. 4x^2 + 3x - 6
Step-by-step explanation:
The values of f(x) for the extremes of x are more positive than the value of f(x) for the middle x, so we know the parabola opens upward. That eliminates choice D.
It is probably easiest to evaluate the other expressions to see which one matches the given f(x) values. For the purpose, it is usually easier to use the Horner form of the equation.
a. f(-2) = (3(-2) +4)(-2) -6 = -2(-2) -6 = -2 ≠ 4
b. f(-2) = (4(-2) +3)(-2) -6 = -5(-2) -6 = 4 . . . . matches the given data point
c. Because (b) matches, we know this one will not.
The appropriate choice is B.
