Question: Powers of 8

Comment on Powers of 8

Can you not immediately subtract the 3 in both the numerator and denominator to get 0? And simplify the rest of the equation?
gmat-admin's picture

In order to apply the Quotient Law (which is covered here https://www.gmatprepnow.com/module/gmat-powers-and-roots/video/1025) the two bases must be equal.

For example, (5^7)/(5^3) = 5^4

In the given expression, the top power has a base of 8^4, and the bottom power has a 8^3, since 8 x 8^2 = 8^3

Since the bases aren't equal, we can't apply the Quotient Law.

Can you guys please tell me that after every question, their is a colour given like green, yellow, red. Can you please tell me that what tgis colour signifies.?
gmat-admin's picture

You bet.

Green: Easy question (difficulty level: 350 to 500)
Yellow: Medium question (difficulty level: 500 to 650)
Red: Difficult question (difficulty level: 650 to 800)

Hi, I'm sorry but where are these colors located in the video? I dont see what you are referring to.
gmat-admin's picture

On each module page (e.g., https://www.gmatprepnow.com/module/gmat-powers-and-roots), you'll see a colored box for each video question. The box is next to the PLAY button.

Oh awesome thanks! Is there an indicator for the verbal section as well because I didn't see it there?
gmat-admin's picture

I don't have the same system for the video questions. However, all of the linked questions (e.g., https://www.gmatprepnow.com/module/gmat-critical-reasoning/video/1136) are categorized by difficulty level.

I am just lost by the title 'Powers of 8'. The rule applies to solve can be applied to any number correct.

Or is it that you decided to name the problem as such
gmat-admin's picture

Yes, the exponent rules needed for this question apply to all bases (not just 8).

I just needed a title for the question to distinguish it from other questions :-)

I first got this question wrong since I did the upper part as (8^9)^3. I keep making mistakes like this (by not first calculating (8^5)(8^4)^3 = (8^5)(8^12)). Which video can I revisit or which practice questions can I do in order to practice and stop making these small mistakes when it comes to what order to perform which mathematic actions in? :-)
gmat-admin's picture

This video covers that concept/law: https://www.gmatprepnow.com/module/gmat-powers-and-roots/video/1029

To practice, you can answer the questions in the Reinforcement Activities area.

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