DS: is x>y ?

[Rag]

if x> 0, is x>y ?

1) 5x - 4y = 3
2) 4y - 5x = 3

Source Petersons

Consider #2
since y=(5/4)x + 3/4
For all values of x>0 , y>x
is B the correct answer?
THe OA is "C"

[esledge]

To the problem as posted, (B) is the correct answer.

I solved this one by graphing, so I put the statements in slope-intercept form and compared the resulting lines to the 45 degree line that is y = x.


1) 5x - 4y = 3
2) 4y - 5x = 3

(1) y = (5/4)x - (3/4) crosses y = x to the right of the y-axis. For some positive x values, (5/4)x - (3/4) < x, but for most positive x values, (5/4)x - (3/4) > x.

(2) y = (5/4)x + (3/4) not only has a slope greater than 1 (45 deg), but also has a y-intercept above (0,0). This line is always above y = x for all x > 0. The answer to "Is x > y?" is a definite No.

I think (C) is the trap answer for those who rephrase to the overly restrictive "What are x and y?"

[Rag]

Thank you much. The official answer is incorrect. I graphed it and came to the same conclusion as you did.

[JonathanSchneider]

: )