Write the standard form of the equation of line passing through the point (-1,-3) and perpendicular to the line x - 4y = 12

1) -4 -y = -7
2) 4x+y = -7
3) x + 4y = -13
4) none of the above

Question

Write the standard form of the equation of line passing through the point (-1,-3) and perpendicular to the line x - 4y = 12

1) -4 -y = -7
2) 4x+y = -7
3) x + 4y = -13
4) none of the above

anonymous · Answer

x-4y = 12
y = (x/4) - 3 

slope of this line is 1/4
but we want line perpendicular to this one so you take the negative reciprocal :
-4

now line equation :
y = y1 + m(x-x1)
y1 = -3
x1 = -1
m = -4

y = -3 + -4(x+1)
y = -3 -4x -4
y = -4x -7
which is 2 since 4x +y = -7  -> y = -4x -7