1. ## quick graph question

Ok, you guys probably will think a preschooler could do this....and you would probably be right..but...the question is...At which of the five points on the graph in the figure above are dy/dx and d^2y/dx^2 both negative.

The answer is B, but I have no idea why. I drew a rough sketch in paint here

Thanks

2. Originally Posted by jst706
Ok, you guys probably will think a preschooler could do this....and you would probably be right..but...the question is...At which of the five points on the graph in the figure above are dy/dx and d^2y/dx^2 both negative.

The answer is B, but I have no idea why. I drew a rough sketch in paint here

Thanks
a preschooler doing calculus? highly unlikely.

$\frac {dy}{dx} < 0$ means the function is decreasing

$\frac {d^2y}{dx^2} < 0$ means the function is concave down

B is the only point that fulfills those conditions