"Decreasing" rate means - sign?
Hi again all,
I answered a related rates type problem from a Calc final and the solution sheet's answer was +6 where my answer was -6:
The equation of a curve in the plane is e^(xy) = x^2 +y^2
A particle is moving along this curve at a certain velocity. At the instant that
it moves through the point (0, 1) the y coordinate is decreasing
at the rate of 3 cm/sec. How fast is the x coordinate changing
at this instant and is it increasing or decreasing.
I interpreted dy/dt as -3 cm/sec but in their answer sheet they marked it as 3, so would I get marks off for something like this?