View Single Post
icosane
#1
May29-09, 03:57 PM
P: 51
1. The problem statement, all variables and given/known data

Within the interval ( -22.27, 40.55 ), for what value of x does f(x) take on a minimum if
f(x)=4.7sin(0.1x)−6.1cos(0.1x)

Later the question asks for the maximum as well.

2. The attempt at a solution

I know to find the critical values to take the first derivative and set it equal to zero, then solve for x. When I do that I get the equation...

0=.47cos(.1x)+.61sin(.1x)

When I solve this guy, by manipulating the equation to get tan(.1x)=-.47/.61, I get only one value, x=-6.56487, which is the minimum value. But I also need a maximum value. I've tried both end points within the interval and they were wrong. Is there something I'm missing here?

Any help would be appreciated.
Phys.Org News Partner Science news on Phys.org
New model helps explain how provisions promote or reduce wildlife disease
Stress can make hard-working mongooses less likely to help in the future
Grammatical habits in written English reveal linguistic features of non-native speakers' languages