GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 14 Oct 2019, 02:36

Close

GMAT Club Daily Prep

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.

Close

Request Expert Reply

Confirm Cancel

Question about simplifying fractions

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Intern
Intern
avatar
Joined: 07 Mar 2019
Posts: 1
Premium Member
Question about simplifying fractions  [#permalink]

Show Tags

New post 08 Mar 2019, 23:16
I recently started studying for the GMAT and my quant skills are lacking. I am struggling to understand why I cannot simply this answer further. This was the final solution to a problem:

\(\frac{zp+q}{x(zp+q)+yp}\)

Why does the zp+q in the numerator and denominator not cancel out? I see it as \(\frac{1}{x+yp}\)

I appreciate any feedback.
Senior Manager
Senior Manager
avatar
P
Status: Manager
Joined: 02 Nov 2018
Posts: 280
Location: Bangladesh
GMAT ToolKit User
Re: Question about simplifying fractions  [#permalink]

Show Tags

New post 08 Mar 2019, 23:31
If yp is multiply with x(zp+q) we can cancel. but in here x(zp+q) +yp is addition form .
that's why we can't cancel (zp+q)
_________________
Give a kudos if u find my post helpful. kudos motivates active discussions :)

General GMAT Forum Moderator
User avatar
V
Joined: 15 Jan 2018
Posts: 598
Concentration: General Management, Finance
GMAT 1: 720 Q50 V37
Premium Member Reviews Badge
Re: Question about simplifying fractions  [#permalink]

Show Tags

New post 09 Mar 2019, 10:50
Not to sound rude, I would recommend that you revisit your math concepts. If you are stuck at such a basic concept, then chances are that you would need work on average to tough areas.

No to answer your query, please remember that ONLY common items cancel out in numerator and denominator.
Let's consider zp+q = A, now the expression becomes \(\frac{A}{xA+yp}\). Do you notice that the term "yp" do not have the so-called common recent A. Hence, A is not actually the common element in the numerator and denominator. Therefore, we cannot cancel out A, i.e zp+q. I hope this explanation helps.

All the best.

_________________
In case you find my post helpful, please provide me with kudos. Thank you!

New to GMAT Club or overwhelmed with so many resources? Follow the GMAT Club Study Plan!
Not happy with your GMAT score? Retaking GMAT Strategies!
Director
Director
User avatar
V
Status: Manager
Joined: 27 Oct 2018
Posts: 669
Location: Egypt
Concentration: Strategy, International Business
GPA: 3.67
WE: Pharmaceuticals (Health Care)
GMAT ToolKit User
Re: Question about simplifying fractions  [#permalink]

Show Tags

New post 12 Mar 2019, 08:39
Hi Zixzix

your question is so basic and fundamental. You have a revise the basic rules of arithmetic.
This thread would help you learn every thing needed for GMAT. Start with the arithmatics, number properties and fractions.
https://gmatclub.com/forum/ultimate-gmat-quantitative-megathread-244512.html
_________________
Thanks for Kudos
Senior Manager
Senior Manager
avatar
G
Joined: 25 Feb 2019
Posts: 336
Re: Question about simplifying fractions  [#permalink]

Show Tags

New post 12 Mar 2019, 09:10
Hi ,

this is a fundamental question.

I would try to explain

we can only cancel in scenario where we have experssion in the form or multiplication

example

x*(x+y)*(y+z)

here these all are in multiply and each one in ()

is considered as a single unit

but if you put + or - then

we have ,

(x+x+y) *(y+z) then these two in () become two units

now x+x+y will be treated as a single unit for division operation

hope it helps

Posted from my mobile device
GMAT Tutor
avatar
G
Joined: 24 Jun 2008
Posts: 1810
Re: Question about simplifying fractions  [#permalink]

Show Tags

New post 14 Mar 2019, 07:22
1
A lot of people have questions like this, and when people start reviewing math again for the GMAT, it's in these kinds of situations where mistakes are most common. When you are canceling in a fraction, anything you cancel must be a factor of the entire numerator and of the entire denominator. So if you want to cancel something, you must be able to rewrite the numerator and denominator as products, where the thing you're canceling is part of each product. So in the basic case, with numbers:

8/36

We can rewrite the numerator and denominator as products, both containing the number '4':

(4)(2) / (4)(9)

and now we cancel the '4' to get 2/9.

The algebraic case is similar. I'll give one example where we can factor and cancel (using quadratic factoring) :

\(\frac{x^2 - 7x + 12}{x^2 - 5x + 6} = \frac{(x-3)(x-4)}{(x-3)(x-2)} = \frac{x-4}{x-2}\)

Notice we can cancel the "x-3" because it is part of a product in both the numerator and denominator. Or in this case you can cancel:

\(\frac{ab + ac}{ab - ac} = \frac{(a)(b+c)}{(a)(b-c)} = \frac{b+c}{b-c}\)

because "a" is a factor of both the numerator and denominator. But in cases like this, say:

\(\frac{xz + y}{xz - y}\)

no cancellation is possible, because there is no identical factor we can create in both the numerator and denominator (in fact there's no factorization we can even do here). So even though the numerator and denominator appear quite similar here, that is no guarantee that any cancellation will be possible - you need to see what factoring you can do.

Factoring is one of the most useful techniques in all of algebra, so if it's something you're not completely comfortable with yet, I'd suggest practicing it a lot, because it's a crucial skill for GMAT math.
_________________
GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com
Intern
Intern
avatar
Joined: 25 Feb 2019
Posts: 5
Location: India
Re: Question about simplifying fractions  [#permalink]

Show Tags

New post 18 Mar 2019, 04:36
IanStewart wrote:
A lot of people have questions like this, and when people start reviewing math again for the GMAT, it's in these kinds of situations where mistakes are most common. When you are canceling in a fraction, anything you cancel must be a factor of the entire numerator and of the entire denominator. So if you want to cancel something, you must be able to rewrite the numerator and denominator as products, where the thing you're canceling is part of each product. So in the basic case, with numbers:

8/36

We can rewrite the numerator and denominator as products, both containing the number '4':

(4)(2) / (4)(9)

and now we cancel the '4' to get 2/9.

The algebraic case is similar. I'll give one example where we can factor and cancel (using quadratic factoring) :

Such a great and helpful answer.

\(\frac{x^2 - 7x + 12}{x^2 - 5x + 6} = \frac{(x-3)(x-4)}{(x-3)(x-2)} = \frac{x-4}{x-2}\)

Notice we can cancel the "x-3" because it is part of a product in both the numerator and denominator. Or in this case you can cancel:

\(\frac{ab + ac}{ab - ac} = \frac{(a)(b+c)}{(a)(b-c)} = \frac{b+c}{b-c}\)

because "a" is a factor of both the numerator and denominator. But in cases like this, say:

\(\frac{xz + y}{xz - y}\)

no cancellation is possible, because there is no identical factor we can create in both the numerator and denominator (in fact there's no factorization we can even do here). So even though the numerator and denominator appear quite similar here, that is no guarantee that any cancellation will be possible - you need to see what factoring you can do.

Factoring is one of the most useful techniques in all of algebra, so if it's something you're not completely comfortable with yet, I'd suggest practicing it a lot, because it's a crucial skill for GMAT math.


Such a great and helpful answer.
Manhattan Prep Instructor
User avatar
G
Joined: 04 Dec 2015
Posts: 833
GMAT 1: 790 Q51 V49
GRE 1: Q170 V170
Re: Question about simplifying fractions  [#permalink]

Show Tags

New post 27 Mar 2019, 17:09
Zixzix wrote:
I recently started studying for the GMAT and my quant skills are lacking. I am struggling to understand why I cannot simply this answer further. This was the final solution to a problem:

\(\frac{zp+q}{x(zp+q)+yp}\)

Why does the zp+q in the numerator and denominator not cancel out? I see it as \(\frac{1}{x+yp}\)

I appreciate any feedback.


The reason is that to simplify a fraction, you have to divide the entire numerator and the entire denominator by the same thing.

In your example, you've divided the whole numerator by zp+q. That is, (zp+q)/(zp+q) = 1, so you've turned the numerator into 1.

However, you've only divided part of the denominator by zp + q. You divided the x(zp+q) part, but you would also have to divide the yp part.

Always divide the whole numerator and the whole denominator, even if there's addition or subtraction in one of them!
_________________
Image

Chelsey Cooley | Manhattan Prep | Seattle and Online

My latest GMAT blog posts | Suggestions for blog articles are always welcome!
GMAT Club Bot
Re: Question about simplifying fractions   [#permalink] 27 Mar 2019, 17:09
Display posts from previous: Sort by

Question about simplifying fractions

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne