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simplest form 2

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Source: — Problem Solving |

by Brent@GMATPrepNow » Fri Aug 26, 2011 11:05 am
marmar29 wrote:4 ( 3X - 2 ) ( 2X + 4 ) + 3X^2 + 5X - 6
in the simplest form is
a- 9X2 + 3X - 14
b- 9X2 + 13X - 14
c- 27X2 + 37X - 38
d -27X2 + 27X - 26
e- 27X2 + 27X - 26
We can save a lot of time by using the process of elimination.

Notice that, when we find the product of 4(3X - 2)(2X + 4), the resulting expression will be ??X^2 + ??X - 32
Notice that we don't care about the other terms just yet. We care only about the term without variables, which will be -32, since (4)(-2)(4) = -32

So, 4(3X -2)(2X + 4) + 3X^2 + 5X - 6 = ??X^2 + ??X - 32+ 3X^2 + 5X - 6
Now, when we combine the like terms, we get:
= ??X^2 + ??X - 38

Since only answer choice C has -38 as the constant term (the term without a variable), the correct answer must be C

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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