I think this is a problem on the mean value theorem? In which case, I think you have to show that there is a point a<c<b where the tangent to the curve is parallel to the line drawn between and .
there is a function f(x) which is continues in the borders [a,b]
and derivitable in the borders (a,b), b>a>0
alpha differs 0
prove the there is b>c>a
in that formula:
i dont know what the purpose of this question
what doi need to do next??