2 quick questions:

Find the equation of the line tangent to the curve y^2+xy+x^3=7 at the point x=2.

Given the function f(x)=ln(3+sinx) on the interval [0,7]

a. at which values of x does f have local max and local min

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- April 30th 2008, 04:02 PMqu2010help please asap
2 quick questions:

Find the equation of the line tangent to the curve y^2+xy+x^3=7 at the point x=2.

Given the function f(x)=ln(3+sinx) on the interval [0,7]

a. at which values of x does f have local max and local min

- April 30th 2008, 04:12 PMJhevon
do you know how to differentiate implicitly? you can do that and solve for y'. you can use that to find the slope. then the equation of the tangent line is given by , just solve for y. Here, is the slope, given by the derivative that you found earlier, is a point the line passes through. it will be you can solve for using the initial equation, you'll need to do this anyway to get the slope.

Quote:

Given the function f(x)=ln(3+sinx) on the interval [0,7]

a. at which values of x does f have local max and local min

To find the critical points, set and solve for (only take the values between 0 and 7 inclusive.

To find whether the point you found above are max's or min's, check the following:

If then we have a local max

If then we have a local min - April 30th 2008, 04:35 PMqu2010
i know how to do both the problems. i wanted to see someone else do the work to see if my answers for the problem were correct. so if you could show your work i would greatly apperciate it.

- April 30th 2008, 04:41 PMJhevon
- April 30th 2008, 04:50 PMqu2010
for the first question i got y= -6x+12

and for the second answer i got local max @ x=2 and local min @ x=5

i dont know if these are correct or not - April 30th 2008, 05:34 PMJhevon
when , we have:

So that we are concerned with the point , this will be our .

Now,

at , the slope is undefined. So that the tangent line is just

Quote:

Given the function f(x)=ln(3+sinx) on the interval [0,7]

a. at which values of x does f have local max and local min

............by the chain rule

for

, so we have a local max at

, so we have a local min at - April 30th 2008, 05:38 PMqu2010
thank you very much