Equation 1: x - 3y = 9
Equation 2: y = -3x + 3
What is the best description for the lines?
A)parallel
B)vertical
C)perpendicular
D)the same line
+9481 x - 3y = 9
Subtract x from both sides.
-3y = -x + 9
Divide both sides by -3 .
y = x/3 - 3 The slope of this line is 1/3 .
y = -3x + 3 The slope of this line is -3 .
Since the slopes of the two lines are negative reciprocals of each other, the lines are perpendicular.
+9481 x - 3y = 9
Subtract x from both sides.
-3y = -x + 9
Divide both sides by -3 .
y = x/3 - 3 The slope of this line is 1/3 .
y = -3x + 3 The slope of this line is -3 .
Since the slopes of the two lines are negative reciprocals of each other, the lines are perpendicular.
