The circumference of Earth is 24,901 miles
Answer:

Step-by-step explanation:
4-xy=y^3
dy/dx=?

Solving for dy/dx: Addind x dy/dx both sides of the equation:

Common factor dy/dx on the right side of the equation:

Dividing both sides of the equation by 3y^2+x:

Answer:
# 2 is correct :)
Step-by-step explanation:
Answer:
x=2.2
y=-3.4
Step-by-step explanation:
subtract the second from the first
-5x=-11
x=2=2
substituting by x in the first equation
so y=-3.4
Answer:
2 gallons of pure alcohol
Step-by-step explanation:
Let x represent the number of gallons of pure alcohol needed, and create an equation:
4(0.25) + x(1) = (x + 4)0.5
1 + x = 0.5x + 2
x = 0.5x + 1
0.5x = 1
x = 2
So, 2 gallons of pure alcohol should be added.