Answer to Question #50188 in Discrete Mathematics for Sajid Mehmood

Question

Without using truth table prove that (p→q)ᴧ(q→r)→(p→r) is a tautology

Answer 1

To make it false
The right side must be false, so (p = T, r = F).
To make the lift side true, so p q must be true since (p=t)so (q =t) and
q r must be true, since (r=f) so (q = f).
So we cannot make it false so it is a tautology.