Given: 2r+3 is not equal
to17
Prove: r is not equal to 7
26. () Therefore, 2r+3
isnot equal to 17 is false
because they are equal
27. () Then 2r +3= 17,
2(7)+3=14+3=17
28. (_) It follows that
r=7
29. (_) Assume
temporarily that r=7
30. (_) But this
contradicts the given fact
that 2r +3 is not equal to
17.​