The symbolic equivalent of the argument is to prove by deduction that p ⇒ q
is true Starting with p, we deduce p ⇒ r ⇒ s ⇒ … ⇒ q This implies that “p ⇒ q” is true Example 2 Prove that the function f : R →
→
→
→
→ R
defined by f (x) = 2x + 5 is one-one