Write the reciprocal and the anti-reciprocal of:

Question

That a quadrilateral has 4 equal sides, is a necessary condition for that it is a square.
That a triangle has 2 equal sides, is a necessary condition for that it is isosceles.
Only if f is integrable in an I interval, f is continuous in I.
If an f function is derivable in a point then f is continuous in that point.
F is not an even function, to less that f(x)=f(-x).
If a<b then a^2< b^2.