What is the equation of the line that is perpendicular to line

y = 2x and passes through point

(a, b) ?

1.

a = -b 2.

a - b = 1 (C) 2008 GMAT Club -

m12#13 * Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient

* Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient

* BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient

* EACH statement ALONE is sufficient

* Statements (1) and (2) TOGETHER are NOT sufficient

Statement (1) by itself is insufficient. It is not possible to construct the equation of the line.

Statement (2) by itself is insufficient. It is not possible to construct the equation of the line

Statements (1) and (2) combined are sufficient. They provide a system of linear equations from which

a = \frac{1}{2} ,

b = -\frac{1}{2} . This is enough to build the equation of the line.

The correct answer is C.

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For me the answer is D. The perpendicular to y = 2x is y = -1/2x

There is no need for the statements to find the perpendicular. The statements are only good for finding values for a and b. For example, statement 1 gives a=b=0.

Could somebody point out what is wrong with my reasoning?

Thanks
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Please kudos if my post helps.