Question 381045
with inequalities we can : 
 
a) add a quantity on both side : {{{a<b}}} then {{{a+c<b+c}}}
 
b) multiply by a positive factor on both side : {{{a<b}}} then {{{ac<bc}}}
 
c) multiply by a negative factor and change sense of inequality
 
 {{{a<b}}} then {{{ac>bc}}} if c<0
 
d) take a growing function {{{a<b}}} then {{{f(a)<f(b)}}} if f growing
  
e) take a decreasing function and change sign, {{{a<b}}} then {{{g(a)>g(b)}}} if g is decreasing