GMATinsight
Which of the following is equivalent to \(\frac{(2x+4)}{[2x^2+8x+8]}\) for all values of x for which both expressions are defined?
A) 1/(2x² + 6)
B) 1/(9x + 2)
C) 2/(x + 6)
D) 1/(x + 4)
E) 1/(x + 2)
sashiim20 has demonstrated the best/faster approach, BUT if you didn't think of that technique, you can still solve the question.
We're looking for an expression that is EQUIVALENT to (2x + 4)/(2x² + 8x + 8)
So, for ANY value of x, the correct answer must evaluate to have the same value as (2x + 4)/(2x² + 8x + 8) does
So, let's plug in a value for x
Let's try x =
1First plug this value into the GIVEN expression.
We get: (2x + 4)/(2x² + 8x + 8) = [2(
1) + 4]/[2(
1²) + 8(
1) + 8]
= 6/18
=
1/3So, the correct answer choice will be the one that evaluates to
1/3 when we plug in x =
1A) 1/(2x² + 6) = 1/[2(
1²) + 6] =
1/8. We want
1/3, so ELIMINATE A
B) 1/(9x + 2) = 1/[9(
1) + 2] =
1/11. We want
1/3, so ELIMINATE B
C) 2/(x + 6) = 2/(
1 + 6) =
2/7. We want
1/3, so ELIMINATE C
D) 1/(x + 4) = 1/(
1 + 4) =
1/5. We want
1/3, so ELIMINATE D
E) 1/(x + 2) = 1/(
1 + 2) =
1/3. BINGO!!
By the process of elimination, the correct answer is
Cheers,
Brent
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