contestada

joaquin and serena are looking at the problem 3x+1>0 serena says that the inequality is always true because multiplying a number by three and then adding one to it makes the number greater than zero, is she right explain why or why not

Respuesta :

AL2006
Unfortunately, Serena is not correct.  She has apparently lost sight of
most of the world of negative numbers.

In fact, if 'x' is ANY number less than negative 1/3, then 3x+1 is less than zero.

There are a huge load of numbers that qualify.
Serena is wrong. She has completely ignored negative  numbers. 
With negative numbers, it is possible to have an answer that is less than zero.
For example, x=-2
3(-2)+1= -5
which is not > than 0.