Question

Line w is perpendicular to the line y=-x-5 and passes through the point (-2,4). What is the y-intercept of line w?

Answer 1

Perpendicular lines have slopes that are the negative reciprocals of each others slopes. this means that you can:
1. write the slope as a fraction (if not already one),
2. flip the fraction over
3. multiply the fraction by - 1
4. And you have perpendicular lines slope.

so the slope of this line is - 1 so:
1. - 1 = - 1/1 convert to fraction
2. - 1/1 = - 1/1 flip but this case stays same
3. - 1/1 * - 1 = 1 multiply by - 1
4. slope is 1

we have slope and point so we can plug into equation:
y = mx + b
with m as slope and b is y intercept.

plug values:
4 = 1 * (- 2) + b
6 = b

so y intercept would be (0,6)