Thread: Intergral help

Over what open interval does the formula F(x)=[int (from 1 to x) dt/t]

represent an antiderivative of f(x)=1/x? and find a point where the graph of F crosses the x-axis.

I don't even how to start calculating this problem.

Thank you

Originally Posted by noppawit

Over what open interval does the formula F(x)=[int (from 1 to x) dt/t]

represent an antiderivative of f(x)=1/x? and find a point where the graph of F crosses the x-axis.

I don't even how to start calculating this problem.

Thank you

hmm, since you are already in the integrals, you should already know the function for which you differentiate it gives .

let . Then .

Thus, by FTOC, , where ..