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Re: The expression (root(8 + root(63)) + (root(8 - root(63))^2 =
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22 Dec 2014, 15:18
Hi registerincog,
Since it's been over a year since you posted, I'm not sure if you're still around to see this, but this question is more about pattern-recognition than anything else.
Bunuel has already shown how the math works, so I won't rehash that here. Instead, I'll offer some perspective.
The GMAT Quant section is going to test you on a lot of standard math rules/ideas/formulas/etc., but will sometimes test you on these rules in ways that you're not used to thinking about. When you find yourself looking at a question that is based on some "crazy-looking" numbers, then chances are really good that the question is built around a pattern of some kind (and it's a pattern that you KNOW in some other simpler format).
Here, if you ignore the numbers and square root signs, you really just have this:
(X+Y)^2
This is one of 3 Classic Quadratics that you MUST have memorized for Test Day.
(X+Y)^2 = X^2 + 2XY + Y^2
Now you can plug back in the relative values for X and Y and simplify. The "math" won't be fun, but its based on standard arithmetic rules (using radicals, multiplication, combining like terms, etc.).
GMAT assassins aren't born, they're made,
Rich