am i missing something?

[JustMe123]

If x and y are positive integers and y = sqrt(9 - x) , what is the value of y?
(1) x < 8
(2) y > 1

SPOILER: i marked E but the Official Answer is D

[skarya]

If x and y are positive integers and y = sqrt(9 - x) , what is the value of y?

=> x>0 and y>0

(1) x < 8
x=1,2,3,4,5,6,7 => y=sqrt(8), sqrt(7), sqrt(6), sqrt(5), sqrt(4), sqrt(3), sqrt(2)
but y is an integer
=> only y=sqrt(4)=2 is valid

sufficient

(2) y > 1
x=1,2,3,4,5,6,7,8 => y=sqrt(8), sqrt(7), sqrt(6), sqrt(5), sqrt(4), sqrt(3), sqrt(2), sqrt(1)

y is a positive integer and
y>1
=>y=2
sufficient

D

[JustMe123]

Skarya, thanks! I missed the fact that y must be an integer!!! This type of errors accounts for 90% of my mistakes....i'm so sad

[skarya]

Skarya, thanks! I missed the fact that y must be an integer!! This type of errors accounts for 90% of my mistakes....i'm so sad

I have been making careless such mistakes sometimes - to improve - I always keep telling myself that Question stems contains vital information and should be looked at closely -

For variables - note if integers or not, +ve, -ve, otherwise must try
-2, -0.5, 0, +0.5, +2 etc. (key is I often used to miss the fractions!)

In DS - always do the condition 2 (so that no carry over of info from condition 1)

Always look for what break the given condition as that is what proves if information given is sufficient or not

[dshweta]

I forgot 0 is neither positive or negative!!! God help me! D it is. y can only be 3.

[skarya]

I forgot 0 is neither positive or negative!! God help me! D it is. y can only be 3.

Shweta, y can only be sqrt(4)=2 NOT 3. Please check (I guess its typo).