Determine how fast the length of an edge of a cube is changing at the moment when the length of the edge is 5cm and the volume of the edge is decreasing at the rate of 100cm^3/sec​

Respuesta :

Answer:

1.333 cm/s

Explanation:

The formula for the volume of the cube V in term of its edge s is:

[tex]V = s^3[/tex]

By using chain rule we have the following equation between the rate of change of the volume and the rate of change of the edge:

[tex]\frac{dV}{dt} = \frac{dV}{ds}\frac{ds}{dt}[/tex]

[tex]100 = \frac{d(s^3)}{ds}\frac{ds}{dt}[/tex]

[tex]100 = 3s^2\frac{ds}{dt}[/tex]

[tex]\frac{ds}{dt} = \frac{100}{3s^2}[/tex]

We can substitute s = 5 cm:

[tex]\frac{ds}{dt} = \frac{100}{3*5^2} = 100 / 75 = 1.333 cm/s[/tex]