In the XY-coordinate plane, line L and line K intersect

[s.pratibha14]

plz suggest how to approach this question?

in XY Plane, line K passes through the point(1,a) and L passes through the (1,b) and both the lines passes through the origin point.
Whether K's Slope greater than the L slpoe?
1. ab>0
2.|a| > |b|

[aspirant_gmat_2012]

Hi Pratibha,

Is the OA = (C)?

Approach:

Use y=mx+c equation. Since lines pass through (1,a) and (1,b) resply, we have:

1=am1 + C1
1=bm2 + C2

Since the lines also pass through (0,0), C1=0 and C2=0.

Hence, m1= (b/a)m2. Therefore, the question is actually is b>a?

(I) : a and b have same signs, not sufficient.
(II): Absolute values are less, not sufficient.

Combined: Sufficient, when both have same signs and |a| > |b| then b is necessarily greater than a.

Hope it helps,
Syed

[s.pratibha14]

Hi Syed,

U have written that

{Use y=mx+c equation. Since lines pass through (1,a) and (1,b) resply, we have:

1=am1 + C1
1=bm2 + C2}


why did u put 1 in place of Y in Y= mX+C
As we know that 1 is x cordinate and a is y cordinate.


Please explain.

and OA is E.

[aspirant_gmat_2012]

Yea, my mistake. This explains why you should not solve quant questions at work ;)

Nevertheless, I think you must have got the answer now. Just use a & b as (3,2) & (-3,-2) to prove & disprove.

[s.pratibha14]

got it :) why did u get it wrong.
I was just wanted to confirm my approach.. its same as u told...

Thanx for ur effort ...

[aspirant_gmat_2012]

I took the points as (a,1) and (b,1).

U r wlcmd,
Syed

[nakul.maheshwari000]

You can also say:
M(k) = a (y2-y1/x2-x1)
M(l) = b

Then just pick numbers.

Option A - ab > 0.
- Does not help here at all. It can be 6.3 > 0 or -6 X -3 > 0

Option B - |a| >|b|
- Does not work either. It can 6 > 3 or |-6| > |-3|

Combine both
Same deal. Both the numbers can be either positive or negative.

Hence Insufficient, Answer - E

[jnelson0612]

It is always great to see students helping each other! Thanks everyone!

[rohansharmaster]

If I consider both lines to have negative slope using option C then must I assume that a slope of -6 is less than a slope of -3 ?
Although -6<-3 but a slope of -6 is steeper than -3 no ?

I'm confused ..

[tim]

you seem to be purposely misinterpreting the definition of "less"..