proof for number 12 13 12 Prove For all abcd e I if a Solut

proof for number 12 & 13.

Solution

12)

Given inequalities

a < b..................(1) and

c < d..................(2)

Adding (1) and (2) we get

a+c < b+d

13) given a < b and c> 0

Since c is positive multiplicatio of c on both sides of the inequality doesnt change the inequzlity

hence multiplying c on both sides of the inequality a < b we get , ac < bc