Graphical Reasoning

[nycmathguy]

Graph the function and determine the
interval(s) for which f(x) ≥ 0.

56. f(x) = 4x + 2

Show me the steps. No sample given by Ron Larson.

 

[MathLover1]

f(x) ≥ 0
0= 4x + 2
4x=-2
x=-1/2

the interval for which f(x) ≥ 0 is [-1/2, infinity)

 

[nycmathguy]

f(x) ≥ 0
0= 4x + 2
4x=-2
x=-1/2

the interval for which f(x) ≥ 0 is [-1/2, infinity)

Where did infinity come from?

All similar questions are set to zero and solved for x. Yes?

What about if the function is f(x) = 1/sqrt{4x + 2}?