Recent content by mmmhmmk

would multiplying the cost to the distance work, instead of dividing? Cost = 15sqrt(x^2+120^2) + 10(300-x) i still need help with the derivative C`= (15)(0.5)(x^2+120^2)^-0.5 + (10)(300-x)`

yup, the distance is what i meant to say, hallsofivy. munaught - there was a similar question in my textbook, just with different numbers. I followed the steps they used for that one and got stuck trying to figure out the derivative, because the textbook does not explain that step. and since...

above ground represents the wire that will be laid above ground on the other side of the river, which costs $10/m under water represents the wire that will be laid under water, across the river, costs $15/m What rule should I use for the equation?

Hi all, I've been stuck on this question for hours and hours, I'm not sure what I'm doing wrong.. The question states, "a new cottage is built across the river and 300 m downstream from the nearest telephone relay station. The river is 120 m wide. to wire the cottage for phone service, wire...