In a coordinate system, a line goes through point (7, x). Is

if a line goes through (7,x)
then x = 7m+c

a) line goes through (x,7) then 7 = mx+c
so (x-7) = m(7-x) there m = -1
Sufficient.

b) x = 28m+c so m = 0
Sufficient

I believe it is D.

Agree D.........case 1: Slope = -1 and Case 2: Slope = 0........!!

I didnt have much to do at 1 in the night. I am just freaking out.
Well if x = 7 then it is just a single point. I agree that it does not give you much information. If the question were posed by Kaplan they would argue that answer is D.
B may very well be the answer.

Assuming X is a constant single unknown with one single value,

stmt 1 & 2 yield slope value of -1 & 0 respectively. Is this a GMAT-ly correct question? What's the answer halle?

I take that back. option one gives us all changing scenario. we can't tell what slope would be w/o knowing what x is. but with option 2 we can tell what slope is w/o even knowing what x is.

so (x-7) = m(7-x) there m = -1
Sufficient.


above is not applicable for x=7

That is an implication, not a truth, about GMAT questions. My friend took GMAT the other day; he got a question with a contradiction.

Lets deal with a contradiction a bit!

1. x is an integer, what is the value of x?

A. (x-5)(x-4) = 0
B. (x-4)(x+6) = 0

2. x is an integer, what is the value of x?

A. (x-5)(x-4) = 0
B. (x+5)(x+4) = 0

If we were to go by the slogans of this board, the second question would not be GMAT-ly correct question!

1a. x belongs to A = {4, 5}
1b. x belongs to B = {4, 6}

AB = {4}, a set with only one member, hence sufficient.


2a. x belongs to C = {4, 5}
2b. x belongs to D = {-4, -5}

CD = { } = null set, hence insufficient.

In other words, the question is asking whether a solution set with *only one* member exists. A null set--a consequence of contradiction--has no members!