By what age are children purposefully using smiling to communicate positive emotions? 6 months 1 year 18 months 2 years

6 months

Explanation:

6 months old babies do not have the ability to decide if something is funny or not. However, they do have the ability to smile when they want to show positive emotions. For example, they can make a lovely smile when they look at their mothers or when they are pleased about something. Babies communicate positive emotions with their smiles even before they can walk or speak.

local max is .5

step-by-step explanation:

the local maximum is for x values between 2 and 4

it looks like the x value is 2.5 and the y value is .5

the secretary of state, appointed by the president with the advice and consent of the senate, is the president's chief foreign affairs adviser. the secretary carries out the president's foreign policies through the state department and the foreign service of the united states.