Answer:
y = -x - 1 (Second answer in list)
Explanation:
Hello! Remember that when two lines are perpendicular, their respective slopes are negative reciprocals of one another.
The given line, y = x + 7, has a slope of 1; therefore, a line perpendicular to y = x + 7 would have a slope of m = -1 (which is the negative reciprocal of 1).
Start with y = mx + b, and substitute -1 for m: y = -1x + b.
Next, subst. 3 for y and -4 for x: 3 = -(-4) + b. Then b = -1, and the desired equation is y = -x -1. This is the 2nd answer in this list.