value of expression

[skarya]

From Set10 #20 (before solving scroll down...)

If x > 0, then 1/[v(2x)+vx] =

A. 1/v(3x)
B. 1/[2v(2x)]
C. 1/(xv2)
D. (v2-1)/vx
E. (1+v2)/vx

This is how it is mentioned in set 10.pdf problem # 20

I am still figuring out what the expression means!

Official Answer:

SPOILER: Not A

...

OKAY figured out whats wrong...

v is actually NOT (letter v) but SQRT - someone tried to use v in place of writing SQRT or ROOT or it's PDF convertors fault that couldn't load proper character for the symbol (the one we draw as √ )...

So question must look like this...

If x > 0, then 1/[SQRT(2x)+SQRTx] =

A. 1/SQRT(3x)
B. 1/[2SQRT(2x)]
C. 1/(xSQRT2)
D. (SQRT2-1)/SQRTx
E. (1+SQRT2)/SQRTx

I am sure everyone will get to Official Answer now...

Official Answer:

SPOILER: D

This applied to some other questions as well in the GMAT Sets e.g. Set 10 # 23 ... Watch out while doing SETS.

[G.Unit]

The answer should be (A)

1/v[2x+x] = 1/v[3x]

[animesh]

1/[SQRT(2x)+SQRTx]
= [SQRT(2x)-SQRTx] /{[SQRT(2x)+SQRTx] [SQRT(2x)-SQRTx]}
= [SQRT(2x)-SQRTx]/[2x-x]
= [SQRT(2x)-SQRTx]/x
= [SQRT 2-1]/SQRTx


So the answer is D.

[chatru]

Ans must be "D"

solu: multiply denominator and numerator by ( sqrt2 + 1) and you see the ans

[Gmatters]

D
mtd exactly as animesh