If x#-y, is x-y/x+y > 1?
1.) x > 0
2.) y < 0
These problems always get me, I tend to pick one as 0, what is correct approach?
Pick numbers and prove 2 answers Y/N?
for f = (x-y)/(x+y) > 1 to be true:
(I) x - y and x + y need to have same sign
(II) abs. value of (x - y) needs to be greater than abs value of (x + y)
(1) x > 0
for y>0 f < 1
for certain value of y < 0 (where |y| < |x|) f > 1
=> A insufficient --> D insufficient
(2) similar argument for y < 0 --> B insufficient
with (1)&(2) combined:
f > 1 if x > |y|
f < 1 if x < |y|
=> C insufficient
--> Answer is E