(-8, -5)
To form a rectangle, all the lines must be perpendicular and parallel. If you draw out the points on a coordinate plane then you can find the answer pretty easily.
Also, this one is easy because all the lines are vertical or horizontal, and when that is the case then you can just see which number in the set hasn't appeared twice (1 appeared twice as an <em>x</em> value, 0 appeared twice as a <em>y </em>value, but -8 has only appeared once as an <em>x</em> and -5 has only appeared once as a <em>y </em>value)
Y=-x-3/2
That's it written in slope intercept form
√(2x+4)=16 square both sides
2x+4=256 subtract 4 from both sides
2x=252 divide both sides by 2
x=126