A probability density function on the interval [a,1] is given by 1/x^2 and outside this interval.the value of the function is zero. The value of a is

I would like to know how to approach this problem.

A probability density function on the interval [a,1] is given by 1/x^2 and outside this interval.the value of the function is zero. The value of a is

I would like to know how to approach this problem.