Hi,
How would you answer this question?
In the xy-plane, the line with equation ax+by+c=0, where abc(does not equal)0, has a slope of 2/3. What is the value of b?
(1) a=4
(2) c=-6
Cheers,
ds - coordinate geometry 2
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- MAAJ
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IMO [spoiler](A)[/spoiler]
In the xy-plane, the line with equation ax+by+c=0, where abc(does not equal)0, has a slope of 2/3. What is the value of b?
ax + by + c = 0
by = -ax - c
y = (-ax - c)/b
y = (-a/b)x - (c/b)
(-a/b) -> must be the slope
(1) a=4
-a/b = -4/b
-4/b = 2/3
-12 = 2b
b = -6 Sufficient
(2) c=-6
y = (-a/b)x - (c/b)
y = (2/3)x - (c/b)
y = (2/3)x - (-6/b)
I believe this is insufficient, because we don't know the value of x and y, and we can't say that b=3 from -a/b = 2/3
What's the OA???![Smile :)](./images/smilies/smile.png)
In the xy-plane, the line with equation ax+by+c=0, where abc(does not equal)0, has a slope of 2/3. What is the value of b?
ax + by + c = 0
by = -ax - c
y = (-ax - c)/b
y = (-a/b)x - (c/b)
(-a/b) -> must be the slope
(1) a=4
-a/b = -4/b
-4/b = 2/3
-12 = 2b
b = -6 Sufficient
(2) c=-6
y = (-a/b)x - (c/b)
y = (2/3)x - (c/b)
y = (2/3)x - (-6/b)
I believe this is insufficient, because we don't know the value of x and y, and we can't say that b=3 from -a/b = 2/3
What's the OA???
![Smile :)](./images/smilies/smile.png)
ccassel wrote:Hi,
How would you answer this question?
In the xy-plane, the line with equation ax+by+c=0, where abc(does not equal)0, has a slope of 2/3. What is the value of b?
(1) a=4
(2) c=-6
Cheers,
"There's a difference between interest and commitment. When you're interested in doing something, you do it only when circumstance permit. When you're committed to something, you accept no excuses, only results."
- tpr-becky
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This is a coordinate geometry question with a line equation - which means that the slope is equal to the variable m in the y = mx + b standard equation - so first we have to get things to that format.
by manipulating this equation we get y = (-a(x) + c)/b - therefore the slope is -a/b. since the problem tells you that the slope is 2/3 that means that -a/b =2/3
1. if we plug in 4 for a we can quickly find b - so AD are left
2. c plays no role in the slope formula so A is the answer.
Best of Luck
by manipulating this equation we get y = (-a(x) + c)/b - therefore the slope is -a/b. since the problem tells you that the slope is 2/3 that means that -a/b =2/3
1. if we plug in 4 for a we can quickly find b - so AD are left
2. c plays no role in the slope formula so A is the answer.
Best of Luck
Becky
Master GMAT Instructor
The Princeton Review
Irvine, CA
Master GMAT Instructor
The Princeton Review
Irvine, CA