Final answer:
The equation of a line is typically obtained using two known points and calculating the slope and y-intercept. However, the original question does not provide points. Based on the provided figures, the line equation y = 3x + 9 is referenced, which is a linear equation with a slope of 3 and a y-intercept of 9.
Step-by-step explanation:
To determine the equation of a line that passes through two points, one must calculate the slope and y-intercept. For this problem, it seems that there might be an error in the question as no points are provided. Typically, you would identify two points (X1, Y1) and (X2, Y2), calculate the slope (m) using the formula m = (Y2 - Y1) / (X2 - X1), and then use one point to solve for the y-intercept (b) by rearranging the slope-intercept form of a line, y = mx + b, to solve for b. However, if we consider the information provided in figure A1, the slope of the line (m) is given as 3 and the y-intercept (b) is 9, leading to the equation y = 3x + 9.
Regarding the linear equations in Practice Test 4, section 12.1, all the options given represent linear equations. All of them have the form y = mx + b, where m is the slope and b is the y-intercept. Therefore, the correct answer would be option D, which includes both options A and B.