Brian L. answered  11/30/19
Pharmacist Specializing In Many Areas of Math and Science
The general equation for a line in slope-intercept form is y = mx + b, where m is the slope of the line and b is the y-intercept. Let's start solving this problem by re-writing the equation of the line 9x + 3y = 8 in slope-intercept form:
- subtract 9x from both sides of the equation to get 3y = -9x + 8
- divide both sides of the equation by 3 to get y = (-9x + 8)/3
- (-9x + 8)/3 can be written as (-9x÷3) + (8÷3),
- which can be simplified to -3x + (8÷3)
- The equation of the line in slope-intercept form is: y = -3x + (8÷3)
Let's remind ourselves what the question is asking us to do. We need to write the equation of a line (in slope-intercept form) that satisfies the following criteria:
- The line is parallel to the line whose equation is y = -3x + (8÷3)
- The line passes through the point (-1, -4)
The key to answering the question is this fact: Two lines must have the same slope in order to be parallel to each other. We now know that m = -3 for this line whose equation we are trying to figure out.
We also know that the point (-1, -4) lies on the line, so we can solve for b by plugging (x = -1) and (y = -4) into the equation:
-4 = (-3)(-1) + b
-4 = 3 + b
-7 = b
The equation of the line in slope-intercept form is
y = -3x - 7
 
     
             
 
 
                     
                    