Question

What is the equation of the line that is perpendicular to -x + y = 7 and passes through (-1, -1)?

Answer 1

see u can write y=x+7
slope of this line is 1
for perpendicularity condition is: (slope of line 1)*(slope of line 2)=-1
hence slope of other line comes out to be -1
now apply
(y-y1)=slope*(x-x1)
(y+1)=-1*(x+1)
so eqn of line is x+y+2=0
cheers :)