So all you need to do if find the min of the function:
f(x)=0.04x^3-4x^2-176x
f'(x)=0.12x^2-8x-176
The only zero for this is x=84.105 <---first
Plug this into f(x) to get f(84.105)=-19300 <---second
Hi there!

Recall the volume of a pyramid is:
V = 1/3(bh)
We are given the volume and side length of the base. Find the area of the base:
A = s²
A = (5xy²)² = 25x²y⁴
Plug in the solved for base:
125x³y³ = 1/3(25x²y⁴)h
To isolate for h, begin by multiplying both sides by 3:
375x³y³ = (25x²y⁴)h
Divide both sides by 25x²y⁴. Use the following exponent property:
xᵃ / xᵇ = xᵃ⁻ᵇ
Thus:
375x³y³ / 25x²4⁴ = 15x/y.
The height must be equal to:

We need to cross multiply
So we start off by multiplying the numerator of the right fraction by the denominator of the left fraction, and the same thing only switched around. We get the equation:
3n=24
divide both sides by 3 to get
n=8
Answer: Each pack of pencils cost $6.
Step-by-step explanation: Rosemary had $25 and was left with $1, so she spent $24 in total for four packages, therefore, you can divide $24 into 4 to find out the individual cost, which is $6.