The features of a role graph can show us many facets of the relationship represented by the function. Let\"s take a look at the more popular graphical features. Be sure to pay attention to the vocabulary and the notation provided in this section.
• To find the y-intercept, collection x = 0, and also solve because that y. Remember: the y-intercept will have actually an x-coordinate of 0. y = f (x) = -2x + 2 y = -2(0) + 2; y = 2 y-intercept: (0,2) (Yes, you can also read the y-intercept, b, from the duty equation if it is in y = mx + b form.) • To find the x-intercept, set y = 0, and also solve because that x. Remember: the x-intercept will have a y-coordinate the 0.
You are watching: How to tell if a function is positive or negative
y = f (x) = -2x + 2 0 = -2x + 2; 2x = 2; x = 1 x-intercept: (1,0)
y-values hopeful ory-values negative
|• The optimistic regions of a role are those intervals where the function is above the x-axis. that is where the y-values are optimistic (not zero). |
• The negative regions the a role are those intervals whereby the role is below the x-axis. it is whereby the y-values are negative (not zero).
• y-values that are on the x-axis space neither confident nor negative. The x-axis is where y = 0.
Some attributes are positive over their whole domain (All y-values above the x-axis.)
Some features are an adverse over their entire domain. (All y-values listed below the x-axis.)