You HAVE to Know How to USE this Formula - GRE and GMAT Math

Описание: Update: I am not available for tutoring! But still alive, :) Meanwhile, so many students have personally recommended Target Test Prep for GRE / GMAT that I asked them for a unique discount code, TestedTutor10, for this link: https://targettestprep.referralrock.c... It's the ultimate formula that comes up relentlessly in the GRE and in the GMAT, and so many students miss marks by not knowing it well enough.


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a2 – b2 = (a + b)(a – b)

The difference of two squares comes up all the time, multiple times per GRE or GMAT test. Most students underestimate it badly.

It is virtually guaranteed to be in your exam. And it’s not enough just to agree with the formula, you know must know it forwards and backwards.

When I say backwards and forwards, I mean it is not just enough to recognise one of those two sides, say an expression such as (x + 4)(x – 4) and say ‘hey, that’s x2 – 42’. You must also recognise an expression such as 4x2 – y2 and know that it equals (2x + y)(2x – y).

If you don’t quite believe that (2x + y)(2x – y), for example, can equal something as simple as 4x2 – y2, try multiplying it out to show yourself how it works.

How is the difference of two squares formula tested?
Let’s do a couple of tough examples to get you ready for prime time GRE and GMAT Math.

(〖(x〗^4- x^2)〖(x〗^4+ x^2) )/(x^4+ x^2 ) – (〖(x〗^4- x^2)〖(x〗^4+ x^2) )/(x^4- x^2 )
= x^4- x^2 – (x^4+ x^2)
= x^4- x^2 – x^4- x^2
= -2x2



If p = (5)6 – (3)4, which of the following is the sum of the unique prime factors of p?
2
8
16
64
98

p = (53)2 – (32)2 = (53 + 32) (53 – 32)
(53 + 32) (53 – 32) = (134)(116)
(134)(116) = (2 x 67) (2 x 2 x 29)

After factorizing exponents, always calculate the value inside the brackets. This is:
(53 + 32)(53 – 32) = (134)(116).

Now, the question wants the sum of the prime factors of this answer, so we must prime factorize these numbers:
(134)(116) = (2x67)(2x2x29).

The three unique prime factors are 2, 29 and 67. The sum of these is 98.



I offer private GRE / GMAT tutoring online at a fixed rate of $140/hr. Please get in touch via the email below, or through my tutoring website: https://www.gretutorlondon.com/

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