Question

(-1,-4); y=1/5x+1

Answer 1

What do you need to do?

Answer 2

write an equation for the line that is
perpendicular to the given and that passes through the given point

Answer 3

y = 1/5x + 1
In this equation your slope is 1/5. However, when you are looking for a perpendicular, the slope you want is the negative reciprocal of the slope of the line you were given. So we want the negative reciprocal of 1/5. To find that, flip the fraction over and change the sign. Therefore, the slope we want is -5/1 or just -5.

Now we have the slope and a set of points so we will use the point slope formula : y - y1 = m(x - x1)
slope(m) = -5
(-1,-4) x1 = -1, and y1 = -4
Now lets sub...
y - (-4) = -5(x - (-1)
y + 4 = -5(x + 1)
y + 4 = -5x - 5
y = -5x - 5 - 4
y = -5x - 9

any questions ?