Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Magoosh is excited to offer you a free GRE practice test with video answers and explanations. If you’re thinking about taking the GRE or want to see how effective your GRE test prep has been, pinpoint your strengths and weaknesses with this quiz!

68% (00:28) correct
31% (00:49) wrong based on 70 sessions

Quantity A

Quantity B

4^(2x)

16^x

A)The quantity in Column A is greater. B)The quantity in Column B is greater. C)The two quantities are equal. D)The relationship cannot be determined from the information given.

If you're not sure where to start, you can always start with PLUGGING IN NUMBERS.

Let's start with an easy value for x. How about x = 0 We get: Quantity A: 4^(2x) = 4⁰ = 1 Quantity B: 16^x = 16⁰ = 1 Okay, the quantities are EQUAL

At this point, we know the correct answer is C or D

Now try some other value for x. How about: x = 1 We get: Quantity A: 4^(2x) = 4² = 16 Quantity B: 16^x = 16¹ = 16 The quantities are still EQUAL

Let's try x = -1 We get: Quantity A: 4^(2x) = 4ˉ² = 1/4² = 1/16 Quantity B: 16^x = 16ˉ¹ = 1/16 The quantities are still EQUAL

Let's try one more value for x. How about x = 2 We get: Quantity A: 4^(2x) = 4⁴ = 256 Quantity B: 16^x = 16² = 256 The quantities are still EQUAL

At this point, we might be reasonably convinced that the two quantities will always be equal. So, you might submit this as the correct answer and move on. In my next post, I'll show you why the correct answer is C

RELATED VIDEO

_________________

Brent Hanneson – Creator of greenlighttestprep.com Sign up for my free GRE Question of the Dayemails

Last edited by GreenlightTestPrep on 30 Jul 2016, 05:57, edited 1 time in total.

NOTE: If you've just begun preparing for the GRE, you might not yet be familiar with the laws of exponents. Nevertheless, here's another approach. Take 16 in Quantity B and rewrite it as 4²

We get: Quantity A: 4^(2x) Quantity B: (4²)^x

Now apply the POWER OF A POWER Law to Quantity B to get: Quantity A: 4^(2x) Quantity B: 4^(2x)

At this point can be certain that the two quantities will always be equal Answer:

I am confused on this one you did: "Let's try one more value for x. How about x = 1 We get: Quantity A: 4^(2x) = 4⁴ = 256 Quantity B: 16^x = 16² = 256" The quantities are still EQUAL"

If x=1, then 4^(2(1))= 4^2= 16 and 16^1=16. How did you get 4^4 and 16^2?

I am confused on this one you did: "Let's try one more value for x. How about x = 1 We get: Quantity A: 4^(2x) = 4⁴ = 256 Quantity B: 16^x = 16² = 256" The quantities are still EQUAL"

If x=1, then 4^(2(1))= 4^2= 16 and 16^1=16. How did you get 4^4 and 16^2?

I guess he meant x = 2, but might mistakenly typed 1.

Anyway the best way to solve this is using algebra than plugging in

I am confused on this one you did: "Let's try one more value for x. How about x = 1 We get: Quantity A: 4^(2x) = 4⁴ = 256 Quantity B: 16^x = 16² = 256" The quantities are still EQUAL"

If x=1, then 4^(2(1))= 4^2= 16 and 16^1=16. How did you get 4^4 and 16^2?

Good catch! I have edited my response accordingly.

Cheers, Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com Sign up for my free GRE Question of the Dayemails