Answer
the equation of a line that is perpendicular to −x+3y=9 is y=-3x-7
Explanation:
Equation of given line is −x+3y=9
we write the equation in y =mx+b to find slope of given line (m)
−x+3y=9
Add x on both sides
3y = x+ 9
Divide by 3 on both sides
Slope of given line = 1/3
Slope of perpendicular line is the negative reciprocal of slope of given line
Slope of perpendicular line = -3
Perpendicular line passes through point (-3,2) that is (x1,y1)
Now we use point slope equation
y - y1 = m (x-x1)
y - 2 = -3(x-(-3))
y - 2= -3(x+3)
y -2 = -3x -9
Add 2 on both sides
y = -3x - 7