User:Al-shap7/Proof of logical inquality 1

If a1 > b1   ,     a2 > b2     prove that    a1 + a2 > b1 + b2                                                      proof a1 > b1

so     a1-b1 > 0

a1-b1 >  a2-a2

a1+a2-b1 >  a2

a1+a2 >  a2+b1   (1)

a2 >  b2

a2-b2 >  0

a2-b2 >  b1-b1

a2+b1-b2 >  b1

a2+b1 >  b1+b2   (2)

from (1) and  (2)

a1+a2 >  a2+b1  >  b1+b2

so   a1+a2  >  b1+b2

--Al-shap7 (talk) 12:27, 23 September 2013 (UTC)