Final answer:
The equation of the line in slope-intercept form is y = 3x + 9. Other forms include point-slope form, standard form, and general form. Slope-intercept form is the most commonly used form of a line's equation.
Step-by-step explanation:
The equation of a line can be written in several forms: slope-intercept form, point-slope form, standard form, and general form.
The slope-intercept form is y = mx + b, where m is the slope of the line and b is the y-intercept. In this case, the slope is 3 and the y-intercept is 9, so the equation in slope-intercept form is y = 3x + 9.
The point-slope form is y - y1 = m(x - x1), where (x1, y1) is a point on the line. Since we know the slope (m = 3) and a point on the line (A: (x1, y1)), we can substitute these values into the point-slope form and simplify to find the equation in point-slope form.
The standard form of a linear equation is Ax + By = C, where A, B, and C are constants. By rearranging the equation in slope-intercept form, we can find the equation in standard form (Ax + By = C).
The general form of a linear equation is Ax + By + C = 0, where A, B, and C are constants. This form allows for more general equations of lines.